Lake Carey
Watershed Assessment
and
Watershed Management Plan
Prepared For:
Lake Carey Cottages Association
Prepared By:
F. X. Browne, Inc.
Engineers • Planners • Scientists
Lake Carey
Watershed Assessment
and
Watershed Management Plan
October 2004
Prepared for:
Lake Carey Cottages Association
Prepared by:
F. X. Browne, Inc.
P.O. Box 401
Lansdale, PA 19446
www.fxbrowne.com
FXB File No. PA1590-01-001
Acknowledgments
This project was funded through a Pennsylvania Department of Environmental Protection
Growing Greener Grant. The grant applicant was the Lake Carey Cottages Association.
Appreciation is extended to the Lake Carey Cottages Association volunteers for their dedication
and commitment to preserving the water quality of Lake Carey. Volunteers that participated in
the project include Pat Bernet, Dr. Walter Broughton, Carol Hetzel, Edward Hetzel, Michelle
Hetzel, Ron Tanner, Steve Pitkin, Hetty Baiz, Dick Daniels, Mary Dobler, David Rinehimer, and
Sally Willoughby.
Special appreciation is extended to Dr. Walter Broughton who was instrumental in obtaining the
Growing Greener Grant and managed and administered the grant from beginning to end. Special
thanks are given to Ed Hetzel who directed and participated in all of the field monitoring and
watershed investigations. He also provided valuable technical assistance in understanding Lake
Carey and its watershed. We would also like to acknowledge the contributions of Brian Oram
and the Center for Environmental Quality at Wilkes University. The Center performed many of
the laboratory analyses for the project.
TABLE OF CONTENTS
Title
Page
Executive Summary ......................................................................................................................... i
1.0
Project Description.............................................................................................................. 1
1.1
Background ............................................................................................................. 1
1.2
Project Objectives ................................................................................................... 2
2.0
Lake Ecology Primer .......................................................................................................... 3
3.0
Lake and Watershed Characteristics ................................................................................... 9
3.1
Lake Characteristics ............................................................................................... 9
3.2
Uses of Lake Carey ................................................................................................. 9
3.2.1 Present Uses ................................................................................................ 9
3.2.2 Impairment of Recreational Uses.............................................................. 11
3.3
Watershed Characteristics ..................................................................................... 11
3.3.1 Geology and Topography ......................................................................... 11
3.3.2 Soils........................................................................................................... 11
3.3.3 Land Uses.................................................................................................. 16
4.0
Water Quality Monitoring Program .................................................................................. 18
4.1
Lake and Pond Monitoring ................................................................................... 18
4.1.1 Monitoring Methodology .......................................................................... 18
4.1.2 Lake and Pond Water Quality Results ...................................................... 23
4.1.3 Lake and Pond Biological Interactions ..................................................... 36
4.1.4 Lake and Pond Trophic State Index .......................................................... 46
4.1.5 Bathymetric Surveys and Sediment Testing ............................................. 48
4.2
Stream Monitoring ................................................................................................ 53
4.3
Alum Studies......................................................................................................... 53
4.4
Groundwater Well Monitoring ............................................................................. 54
4.5
Water quality Summary and Conclusions............................................................. 55
5.0
Watershed Evaluations...................................................................................................... 56
5.1
Streambank and Shoreline Erosion ....................................................................... 56
5.2
Road and Driveway Erosion ................................................................................. 56
5.3
Construction and Other Erosion Sites ................................................................... 59
5.4
Failing Septic Systems .......................................................................................... 59
6.0
Pollutant Loadings to Lake Carey..................................................................................... 60
6.1
Hydrologic Budget ................................................................................................ 60
6.2
Phosphorus Loadings ............................................................................................ 61
6.3
Phosphorus Modeling ........................................................................................... 61
6.3.1 Evaluation of Models ................................................................................ 62
6.3.2 Modeling Results ...................................................................................... 63
6.4
Phosphorus Reduction Requirements ................................................................... 63
TABLE OF CONTENTS, CONTINUED
Title
Page
7.0
Lake and Watershed Management Plan ............................................................................ 64
7.1
Goals ..................................................................................................................... 64
7.2
Overview of Management Plan ............................................................................ 64
7.3
Watershed Management........................................................................................ 65
7.3.1 Control of Existing Erosion and Stormwater Runoff ............................... 65
7.3.2 Control of New Development and Related Erosion and Stormwater
Runoff .................................................................................................................. 74
7.3.3 Control of Erosion and Stormwater Runoff from Agriculture.................. 77
7.4
Wastewater Management ...................................................................................... 77
7.4.1 On-Site Wastewater System Solutions ..................................................... 80
7.4.2 Decentralized Wastewater ........................................................................ 82
7.4.3 Centralized Wastewater System ............................................................... 86
7.4.4 Act 537 Plan Revision .............................................................................. 87
7.5
In-Lake Management ............................................................................................ 87
7.5.1 Lake Dredging .......................................................................................... 87
7.5.2 Lake Aeration............................................................................................ 89
7.5.3 Phosphorus Inactivation ............................................................................ 90
7.6
Public Education ................................................................................................... 90
7.7
Water Quality Monitoring..................................................................................... 91
8.0
Implementation of Lake and Watershed Management Plan ............................................. 93
8.1
Watershed Management Implementation ............................................................. 93
8.2
Watershed Planning and Education Implementation ............................................ 93
8.3
In-Lake Management Implementation .................................................................. 94
8.4
Implementation Schedule...................................................................................... 94
8.5
Funding Sources.................................................................................................... 95
9.0
References ......................................................................................................................... 97
APPENDICES
A
B
C
D
E
F
G
H
I
Glossary of Lake and Watershed Management Terms
Dissolved Oxygen and Temperature Profile Data
Water Quality Data
Phytoplankton Data
Zooplankton Data
Sediment Testing Data
Stream Water Quality Data
Jar Testing Data
Well Water Quality Data
LIST OF TABLES
Table
3.1
3.2
3.3
4.1
4.2
4.3
4.4
5.1
6.1
6.2
7.1
Page
Morphometric and Hydrologic Characteristics of Lake Carey ........................................... 9
Lake Carey Soils ............................................................................................................... 12
Land Use in Lake Carey Watershed ................................................................................. 16
Lake Carey Nitrogen- Phosphorus Ratios - Lake Station ................................................. 36
Lake Carey Nitrogen- Phosphorus Ratios - Pond Station ................................................. 36
Lake Carey 2004 Stream Monitoring ............................................................................... 53
Groundwater Well Monitoring Results in Lake Carey Watershed ................................... 54
Nonpoint Source Pollution Problem Areas in Lake Carey Watershed ............................. 58
Phosphorus Loads to Lake Carey ..................................................................................... 61
Total Phosphorus Pollutant Loading to Lake Carey ......................................................... 63
Quantitative Water Quality Goals for Lake Carey ........................................................... 64
LIST OF FIGURES
Figure
3.1
3.2
3.3
3.4
4.1
4.2
4.3
4.4
4.5
4.6
4.7
4.8
4.9
4.10
4.11
4.12
4.13
4.14
4.15
4.16
4.17
4.18
4.19
4.20
4.21
4.22
Page
Lake Carey Watershed Boundary ..................................................................................... 10
Soils in the Lake Carey Watershed ................................................................................... 14
Soil Erosion Hazard in the Lake Carey Watershed .......................................................... 15
Land Uses in the Lake Carey Watershed .......................................................................... 17
Lake and Pond Sampling Locations ................................................................................. 19
Dissolved oxygen profiles at Lake Carey lake station during 2003 ................................. 25
Temperature profiles at Lake Carey lake station during 2003 .......................................... 25
Dissolved oxygen profiles at Lake Carey lake station during 2004 ................................. 25
Temperature profiles at Lake Carey lake station during 2004 .......................................... 25
Dissolved oxygen profiles at Lake Carey pond station during 2003 ................................ 26
Temperature profiles at Lake Carey pond station during 2003 ........................................ 26
Dissolved oxygen and temperature profiles at Lake Carey pond station during 2004 ..... 26
Secchi disk transparency at Lake Carey during 2003 ....................................................... 28
Secchi disk transparency at Lake Carey during 2004 ....................................................... 29
Surface phosphorus concentrations at Lake Carey during 2003 ....................................... 30
Surface phosphorus concentrations at Lake Carey during 2004 ....................................... 30
Hypolimnetic phosphorus concentrations at Lake Carey during 2003 ............................. 32
Hypolimnetic phosphorus concentrations at Lake Carey during 2004 ............................. 32
Surface total nitrogen concentrations at Lake Carey during 2003 .................................... 34
Phytoplankton density at Lake Carey lake during 2003 ................................................... 38
Phytoplankton biomass at Lake Carey lake during 2003.................................................. 38
Phytoplankton density at Lake Carey pond during 2003 .................................................. 39
Phytoplankton biomass at Lake Carey pond during 2003 ................................................ 39
Algal assay results for Lake Carey lake during 2003 ....................................................... 41
Algal assay results for Lake Carey pond during 2003 ...................................................... 41
Algal assay results for Lake Carey lake during 2004 ....................................................... 42
LIST OF FIGURES, CONTINUED
Figure ....................................................................................................................................... Page
4.23
4.24
4.25
4.26
4.27
4.28
4.29
4.30
4.31
5.1
7.1
7.2
7.3
7.4
7.5
7.6
7.7
7.8
Algal assay results for Lake Carey pond during 2004 ...................................................... 42
Chlorophyll a concentrations in Lake Carey during 2003 ................................................ 44
Chlorophyll a concentrations in Lake Carey during 2004 ................................................ 44
Trophic State Indices at Lake Carey during 2003 ............................................................ 47
Trophic State Indices at Lake Carey during 2004 ............................................................ 47
Bathymetric Map of Lake Carey Lake.............................................................................. 49
Sediment Thickness Map of Lake Carey Lake ................................................................. 50
Bathymetric Map of Lake Carey Pond ............................................................................. 51
Sediment Thickness Map of Lake Carey Pond ................................................................. 52
Nonpoint Source Pollution Problem Areas in the Lake Carey Watershed………………57
Existing and Proposed Conditions - Road 1……………………………………………..70
Existing and Proposed Conditions - Road 2……………………………………………..71
Existing and Proposed Conditions - Road 3……………………………………………..72
Bioretention-Swale Treatment Systems………………………………………………….73
Conventional Septic System ............................................................................................. 78
Suitability of Soils in the Lake Carey Watershed for Septic Systems .............................. 79
Suitability of Soil for Drip, Spray & Mound Treatment Systems Based On
Groundwater Level and Slope .......................................................................................... 81
Wastewater Treatment Facility Options…………………………………………………85
F. X. Browne, Inc.
Executive Summary
Overview
Lake Carey is a 254-acre lake with a watershed area of 4,173 acres located in Wyoming County,
Pennsylvania. It consists of a 183-acre upper lake and a 71-acre lower pond. The upper lake is a
natural glacial lake while the lower pond was created to power a sawmill. Lake Carey is used for
recreation, including fishing, boating, swimming and ice skating.
Development pressure in the Lake Carey watershed has increased during recent years,
representing a serious threat to an already damaged watershed. The apparent increase in algae
and aquatic plants has led to a heightened community concern about water quality at the Lake.
This concern was reinforced in 2001 when the EPA approved a TMDL (Total Maximum Daily
Load) for Lake Carey proposed by the Susquehanna River Basin Commission. The
Commission’s study indicated that phosphorus was the “limiting” nutrient and called for a 67 %
reduction in total phosphorus.
Historically, agricultural land use has contributed significant amounts of phosphorus to Lake
Carey. However, the Wyoming County Conservation District and the National Resource
Conservation Service (NRCS) have implemented agricultural Best Management Practices in the
watershed which have likely reduced the amount of phosphorus entering the lake from this land
use. Nonpoint source pollution arising from residential development around the lake is now an
equal or greater concern.
In a visioning process conducted by the Lake Carey Cottages Association in the summer of 2001,
lake residents ranked the lake’s water quality their greatest concern. Consequently, the
Association applied for and received a Growing Greener grant in 2002 to evaluate the water
quality of Lake Carey, determine the sources of pollution, and develop strategies for improving
the quality of the lake through in-lake and watershed restoration measures.
In order to meet these goals, the primary objectives of this project were to:
1.
Determine the present trophic state and overall water quality of Lake
Carey;
2.
Develop an annual total phosphorus budget for the lake and determine the
sources of phosphorus loading to the lake;
3.
Develop an inventory of nonpoint source problem areas in the watershed;
and
4.
Develop a comprehensive lake and watershed management plan.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
i
F. X. Browne, Inc.
Lake and Watershed Characteristics
The water quality in Lake Carey has deteriorated severely over the last 100 years from excessive
nutrient and sediment inflows, a result of agricultural and residential uses in the lake’s
watershed. Extremely low dissolved oxygen concentrations in the lake’s bottom waters release
nutrients from the lake’s sediments causing algae blooms and damaging the habitat for fish.
During the summer, excessive algal growth causes a reduction in water transparency. Many
residents have complained about the lack of water clarity and its ‘green’ color. An apparent
increase in aquatic plant growth in some areas of the lake also has led some to complain of
impaired fishing and boating. Most seriously, a high proportion of the algae which periodically
bloom in the lake are blue-green, and represent a potential health hazard.
All of the soils in the watershed are rated as “severe” for conventional septic systems due to a
seasonably high water table and low percolation rates. However, some soils in the watershed are
acceptable for elevated sand mounds, spray irrigation systems, or drip irrigation systems.
The banks of Lake Carey are protected by forested areas to the north, but most of the lake is
surrounded by year-round and seasonal homes that use septic systems for wastewater disposal
with little vegetative buffer between the homes and the lake. Only about 5 percent of the Lake
Carey watershed is developed, but most of that development is concentrated around the lake and
pond. The majority of the 4,200 acre watershed is either forests or farm land.
Water Quality Monitoring Program
The results of the monitoring program indicate that Lake Carey should be classified as eutrophic
to hyper-eutrophic. (This program included measures of total phosphorus concentration,
chlorophyll a concentration, Secchi disk transparency, and Carlson's Trophic State Index, as well
as U.S. EPA trophic state criteria.) Lake Carey has thus become an “ecologically old” lake, in
danger of siltation and eventual transformation into swamp land and forest. Although this is a
natural process which occurs in all lakes, it has been accelerated here, as elsewhere, by human
activity in the watershed.
Because the phosphorus concentrations in Lake Carey are very high, the limiting nutrient in both
the lake and pond now appears to be nitrogen. Microscopic plants (phytoplankton) are very
common in the main lake and the pond, and undesirable blue-green algae species dominate this
population. Stream water quality monitoring results show that excessive amounts of phosphorus,
sediment, and bacteria are entering Lake Carey during storms.
Results of groundwater well testing indicate that many of the tested wells in the watershed are
contaminated with chemicals, nutrients, and coliform bacteria. This further suggests that failing
septic systems are a major water quality problem (as well as a potential health problem). This
groundwater discharges into Lake Carey, making it more eutrophic. Bacteria concentrations in
Lake Carey, however, do not exceed PA Code Chapter 93 regulations for recreational water
contact or potable water supply.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
ii
F. X. Browne, Inc.
The bathymetric (bottom contour) survey of Lake Carey indicates that the lake has a mean depth
of 18.4 feet and a water volume of 5,414,000 cubic yards. The sediment volume is 1,203,021
cubic yards, with a mean sediment depth of 4.1 feet. The pond has a mean depth of 3 feet and a
water volume of 338,431 cubic yards. The sediment volume is 291,200 cubic yards with a mean
depth of 2.6 feet.
Watershed Evaluations
Volunteers from the Lake Carey Cottages Association investigated nonpoint source pollution
problem areas in the Lake Carey Watershed. The typical problems they identified were
streambank erosion, shoreline erosion, roadside erosion, erosion from driveways, construction
site erosion, and failing on-site wastewater systems.
Pollutant Loadings
The Meade Brook subwatershed is the largest source of water to Lake Carey. Based on the net
total volume of water entering the lake and the lake’s volume, Lake Carey has a hydraulic
residence time of 0.479 years or 171 days.
The model employed in this study estimates the largest source of phosphorus loading in the lake
to be from the sediment already present in the lake and from septic systems (some 46%),
agriculture in the surrounding watershed is thought to be the next largest source (approximately
37%).
Total Phosphorus Pollutant Loading to Lake Carey
Land Use
Mixed Agriculture
Mixed Forest
Residential
Open Water
Septic Systems & Internal Loading
Totals
Loading (lb/year)
1806
384
342
79
2262
4874
Percent Load
37
8
7
2
46
100
The present study calls for a reduction in the phosphorus loading of 3,436 lbs. per year (or 70%
of the present annual loading) to attain a borderline eutrophic condition. This TMDL is based on
a conservative lake model; therefore, it is possible that a smaller reduction, in the 50% range,
may provide a significant improvement in the water quality of Lake Carey.
Lake and Watershed Management Plan
The main goals of this management plan are to protect Lake Carey from further degradation and
to improve its condition to a mesotrophic or borderline eutrophic condition, restoring the lake to
“ecological middle age.” The ultimate objectives, therefore, are to significantly reduce the
nitrogen and phosphorus loadings, to reduce the phytoplankton density, and to reduce the
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
iii
F. X. Browne, Inc.
dominance of blue-green algae. This last goal is important because these algae give off toxins
that can adversely affect aquatic life and humans.
The lake and watershed management plan consists of the following:
Watershed Management
1.
Existing erosion and stormwater runoff should be controlled by:





2.
Rebuilding existing problem areas to reduce or eliminate
erosion and polluted stormwater runoff,
Encouraging home and business owners to implement practices
that reduce or eliminate erosion and polluted runoff from their
sites,
Installing vegetation along shorelines and streambanks to
stabilize the banks and to filter stormwater runoff,
Stabilizing eroded streambanks and shorelines with vegetation,
and
Stabilizing the gravel roads on steep slopes in the watershed
and installing plant filled catchment basins to filter road runoff.
New development and its effects should be limited and controlled by:







Encouraging landowners in the watershed to adopt
conservation easements, especially on lands around sensitive
areas such as streams, lakes, and wetlands,
Adopting a Riparian Buffer Ordinance to require a 75-foot
vegetated buffer along both sides of wetlands and streams, and
a 50-foot vegetated buffer around lake and pond shorelines in
the watershed for all new construction projects,
Adopting a Conservation Ordinance to require the
identification and protection of all natural site features such as
wetlands, waterbodies and trees,
Ensuring that proper erosion and sediment control measures are
installed and maintained during any new construction,
Requiring that erosion and sediment control plans are required
for all earthmoving activities, including the construction of
individual homes,
Adopting a Stormwater Management Ordinance that controls
the volume and quality of stormwater runoff from the 2-year,
24-hour storm. The ordinance should require that low impact
development concepts be integrated into all site development
plans, and
Revising the existing zoning ordinances to reflect the concepts
and provisions of the new stormwater management ordinance.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
iv
F. X. Browne, Inc.
3.
Erosion and Stormwater Runoff from agricultural lands should continue to
be reduced with the assistance of the NRCS and the County Conservation
District. All farmers should have an approved Conservation Plan and a
Nutrient Management Plan.
Public Education Program
The existing public education program for the Lake Carey watershed should be expanded to
educate lake users, homeowners, developers, elected and appointed officials, students, and other
stakeholders about lake ecology, stormwater, septic systems, wastewater management, and the
hazards of further development.
Wastewater Management
Wastewater management is needed to significantly reduce the nutrient loading to Lake Carey
caused by failing septic systems. This should be a high priority. Specific recommendations
include:
1.
Evaluate the feasibility of both decentralized and centralized wastewater
management systems to treat wastewater from failing septic systems.
2.
Conduct a new 537 Wastewater Management Plan study to revise the
existing plan. The study should evaluate both decentralized and
centralized wastewater treatment systems. It should evaluate on-site
options such as mound systems, drip irrigation, and spray irrigation. It
should evaluate innovative systems such as the Septic Tank Effluent Pump
(STEP) to reduce construction and operating costs. It should also evaluate
a variety of treatment plant options.
In-Lake Management
In-lake restoration measures that should be investigated include:

Dredging the pond and/or spot dredging the lake in order to increase water
depth and reduce internal nutrient loading from phosphorus-laden
sediments,

Installing a bottom water (hypolimnetic) aeration system in the lake to
increase the dissolved oxygen concentrations in the bottom waters and
reduce internal nutrient loading, and

Incorporating a continuous alum system into storm sewer inlets and/or
incoming streams in order to reduce external phosphorus loads in
stormwater runoff.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
v
F. X. Browne, Inc.
All of these in-lake options would require feasibility studies to determine their effectiveness
prior to implementation. A dredging feasibility study is a high priority since dredging the pond
would remove a significant amount of nutrients and would significantly reduce the internal
loading of phosphorus there. Aeration and alum treatment measures should be further evaluated
after nutrients from failing septic systems and watershed erosion and runoff have been
significantly reduced.
Water Quality Monitoring Program
The water quality monitoring program should be continued in a modified form. Both the lake and
major streams should be tested to provide historical data that will quantify any changes in the
lake due to the implementation of this management plan. Surveys of large aquatic plants
(macrophytes) should be conducted to document the species present and determine whether any
of those macrophytes are non-native, invasive species.
Implementation of Lake and Watershed Management Plan
Implementation of the recommended management plan can be organized into short-term and
long-term action plans, as follows:
Short-Term Action Plan
The short-term action plan should consist of the following:
1.
Submit Growing Greener Application to:

Control Existing Stormwater Problem Areas

Expand Public Education Program

Develop Municipal Ordinances
2.
Implement Expanded Public Education Program
3.
Perform 537 Wastewater Management Plan Revision and Evaluate:

Decentralized Systems

Centralized Systems

Funding Sources
4.
Encourage Conservation Easements and Develop or Revise Existing Ordinances:

Conservation Easements

Riparian Buffer Ordinance

Conservation Ordinance

Stormwater Management Ordinance

Zoning Ordinance
5.
Investigate the Feasibility of Dredging the Pond and/or Spot Dredging of
the Pond and Lake.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
vi
F. X. Browne, Inc.
6.
Evaluate Funding Opportunities

Growing Greener Program

Penn Vest

Special Appropriations
7.
Continue Modified Water Quality Monitoring Program
Long-Term Action Plan
The long-term action plan is designed to be performed after progress has been made on reducing
the sediment and nutrient loadings from failing septic systems and watershed erosion and runoff.
Some elements of the long-term action plan could be performed concurrently with the short-term
action plan. The long-term action plan consists of the following:
1.
Investigate the Feasibility of Installing a Hypolimnetic Aeration System in
the Lake.
2.
Investigate the Feasibility of Adding Alum to Meade Brook to reduce the
phosphorus load to Lake Carey.
3.
Implement Dredging of Pond and/or Lake Based on Feasibility Study
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
vii
F. X. Browne, Inc.
1.0
Project Description
1.1
Background
Lake Carey is a 254 acre natural lake draining 4,173 acres of forested, agricultural, and
residential land in Tunkhannock and Lemon Townships, Wyoming County, as shown in Figure
1.1. The lake consists of an upper 183-acre lake and a lower 71-acre pond. The lake is glacial in
origin and was raised approximately 4.5 feet to form the pond for a sawmill turbine in the past.
The lake and pond are owned by the Commonwealth of Pennsylvania and the surrounding land is
owned by individual private owners. No public boat launch exists on the lake; however, boat
launching is available at a private marina for a fee. Boat rentals are available at Lake Carey, and
power boats are permitted on the lake.
Lake Carey was originally known as Barnum’s Pond, named after Elijah Barnum who owned a
sawmill at the outlet of the lake as early as 1800. The lake eventually was renamed to Lake
Carey, after Earl H. Carey, a blind man who maintained his title to the land under the lake. The
oldest cottage on the lake was built in 1874 by Dr. T. J. Wheaton. The Pollner House, built in
1877, was the first of several hotels that sprang up to accommodate visitors from Scranton,
Wilkes Barre, and beyond. By July 1884, about 20 cottages were built next to the lake. Today
there are approximately 300 homes surrounding the lake.
On June 2, 1998 a tornado touched down
in a large portion of Wyoming County and
caused significant damage to the Lake
Carey Watershed. Besides the destruction
to the many homes around the lake, many
of the trees in the watershed were either
uprooted or snapped off. The destruction
to the forested areas in the watershed most
likely has had a negative impact on the
water quality of Lake Carey.
Lake Carey is fed by two streams flowing
though marshy ground. The main tributary
to the lake is Meade Brook which drains
the northern portion of the watershed. An Devastation from June 2, 1998 Tornado at Lake
unnamed tributary drains the western Carey
portion of the watershed and include
Bartron and Mud Ponds which are significant waterbodies in the watershed. The lake is also fed
by springs. Water leaves Lake Carey Pond and drains into Billings Mill Brook.
Lake Carey is used for a variety of activities including fishing, boating, swimming and ice
skating. The reported increase in algae and aquatic plants has led to concern about the quality of
Lake Carey and its recreational uses. According to a 1981 PA DEP report (Ulanoski et. al.,
1981), an incidence of a toxic reaction to an Anabaena bloom occurred during 1979. Therefore,
the presence of blue-green algae in the lake is a public health concern as well.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
1
F. X. Browne, Inc.
Development pressure in the Lake Carey watershed has increased during recent years. More
homes are being built around the lakeshore, and more of the existing cottages are being expanded
and converted to year-round homes. This has had a negative impact on Lake Carey water quality,
especially when the existing septic systems are not adequately designed to support the increased
use. More homes around the lake has lead to less shoreline vegetation to filter stormwater runoff
entering the lake, a greater risk of shoreline erosion, and an increase in household chemicals or
lawn fertilizers entering the lake.
In March 2001, the Susquehanna River Basin Commission performed a water quality study at
Lake Carey in order to develop a Total Maximum Daily Load (TMDL) for the lake. A TMDL is
a calculation of the maximum amount of a pollutant that a waterbody can receive and still meet
water quality standards, and an allocation of that amount to the pollutant's sources. The Lake
Carey TMDL was designed to address concerns about summer algae blooms caused by excess
nutrients.
The TMDL study determined that phosphorus is the limiting nutrient in Lake Carey, and
therefore the nutrient that should be targeted for reduction. The recommended reduction in total
phosphorus was 67 percent, or a reduction from 2,585 pounds per year to 860 pounds per year.
Other general recommendations in the report included monitoring the success of agricultural best
management practices (BMPs) implemented in the watershed, reducing nutrient loading from
failing septic systems and the surrounding watershed, and investigating methods of reducing
internal phosphorus loading via in-lake management practices. The TMDL study did not
evaluate watershed BMPs or outline a specific plan for in-lake or watershed BMP
implementation.
1.2
Project Objectives
The Lake Carey Cottages Association is a group of lake residents that are concerned with the
water quality of Lake Carey. In 2002, the Association received a Growing Greener grant to take
the 2001 TMDL study a step further by conducting an evaluation of Lake Carey and developing
this Lake and Watershed Management Plan. Volunteers from the Association assisted with the
water quality monitoring program, the bathymetric survey, and the watershed investigations.
The goals of this project were to evaluate the water quality of Lake Carey, determine the sources
of pollution, and develop strategies for improving the quality of the lake through in-lake and
watershed restoration measures. In order to meet these goals, the primary objectives of this
project were to:
1. Determine the present trophic state and overall water quality of Lake Carey;
2. Develop an annual total phosphorus budget for the lake and determine the sources of
phosphorus loading to the lake;
3. Develop an inventory of nonpoint source problem areas in the watershed; and
4. Develop a comprehensive lake and watershed management plan.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
2
F. X. Browne, Inc.
2.0
Lake Ecology Primer
Ecological Cycle
Note: A lake and watershed glossary is provided in Appendix A for reference purposes.
In a lake, a basic ecological cycle
exists. Aquatic plants like algae
(microscopic aquatic plants) and
macrophytes (large aquatic plants)
require nutrients such as phosphorus
and nitrogen along with sunlight to
grow. Small aquatic animals such as
invertebrates (rotifers, protozoa,
etc.), snails and insects eat the algae
and reproduce. Small forage fish eat
the small animals, and, in turn are
eaten by larger game fish and other
animals. This relationship is called
the ecological, or energy pyramid.
In a healthy lake, this ecological
system exists in proper balance.
THE ENERGY PYRAMID
SOLAR ENERGY
Carnivores
Herbivores
When too many nutrients enter a
lake, the algae and/or large aquatic
plants grow to a point of excess.
With a larger population of algae
one would expect a nice, large
population of fish. However, in
reality the excessive plant life is not
transferred up the food chain. The small aquatic animals do not eat much of the excess algae
(they do not like some of the algae, especially the blue-green algae). Therefore, algae and other
plants build up in the lake and destroy the ecological balance of the lake ecosystem. This can
result in a reduction in the fish population. It often results in a change in the type of fish found in
the lake.
In order to understand the processes that occur in a lake, we must first understand the concept of
lake succession or aging.
Lake Succession Over Time
All lakes go through an aging process called ecological succession. Succession is a natural
process whereby a lake starts out as an “ecologically” young lake with little vegetation, few
nutrients, clear water, and very little unconsolidated (loose) sediment on the bottom. It should be
noted that ecological age is different than chronological age. The chronological age is simply the
number of years a lake has existed. The ecological age, on the other hand, is a measure of the
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
3
F. X. Browne, Inc.
physical, chemical, and biological conditions of a lake. A lake may be chronologically young
(i.e. built only 3 years ago), but it could be ecologically old.
As a lake ages, more nutrients and sediments enter the lake from the surrounding watershed.
Usually, the additional nutrients, such as phosphorus and nitrogen, cause an increase in the
amount of algae and aquatic weeds. The additional sediment entering the lake settles to the
bottom of the lake, increasing the amount of sediment on the lake’s bottom.
Thus as a lake ages, it slowly starts to fill up with sediments, algae and aquatic weeds. Initially,
the aquatic vegetation is submergent vegetation, beneath the water surface. As the lake fills up
further with sediment, emergent vegetation appears above the water surface.
Ultimately, the lake fills in completely with incoming sediment from the watershed and from
dying algae, aquatic plants, and animals. The lake transforms into a pond or swamp and
eventually, over hundreds or thousands of years, into a forest.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
4
F. X. Browne, Inc.
Lake Aging
Lake succession or aging is a natural process that occurs in all lakes. However, the influence of
human activities in the watershed can significantly accelerate the aging process. The lake aging
process is accelerated by:
Wastewater Treatment Plant
Discharges
Agricultural Activities (cropland
and pastureland)
Developed Land
Malfunctioning Septic Systems
Construction Activities
Roadways
Streambank Erosion
Landfills
Human activities in a watershed can add sediments and nutrients such as phosphorus and
nitrogen to a lake, resulting in accelerated aging or “cultural eutrophication”.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
5
F. X. Browne, Inc.
Lake Classification
Lakes are classified by the amount of nutrients (or food) contained in the lake. The Greek word
for food is “trophic”. Therefore, we classify lakes by their “trophic” or food/nutrient state. Such
as:
Oligo = little (little nutrients)
Meso = medium (medium nutrients)
Eu = too much (too much nutrients)
The trophic state refers to the “ecological” age of the lake, not its
chronological age. Therefore, an oligotrophic lake is a lake that
is ecologically young. Lakes are classified by nutrient level and
the presence of aquatic plants as described below.
Oligotrophic lake
ecologically young lake
low level of nutrients
low population of algae and aquatic plants
Mesotrophic lake
ecologically middle-aged lake
moderate level of nutrients
moderate population of algae and aquatic plants
Eutrophic lake
ecologically old lake
high level of nutrients
high population of algae and aquatic plants
Lake Problems
Excessive nutrients entering a lake from its watershed cause algae blooms, excessive aquatic
plants (macrophytes), lake siltation (settling of sediments in lake, loss of lake volume and
capacity), and fishery problems (low dissolved oxygen levels change the fish from game fish to
trash fish such as carp). This results in loss of recreation and other lake uses, and can reduce
property values around the lake.
Lake problems are caused by point sources and nonpoint sources of pollution. Point sources are
wastewater treatment plant discharges. Nonpoint sources cannot be traced to a specific origin,
but seems to flow from many different sources.
Nonpoint Source Pollution
Nonpoint source pollution involves three natural processes: stormwater runoff, erosion and
sedimentation. Rainwater flowing across land and entering rivers and lakes is known as
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
6
F. X. Browne, Inc.
stormwater runoff. The force of runoff breaking up the soils and detaching individual soil
particles is termed erosion. The soil particles are eventually deposited into nearby streams and
rivers. This process is called sedimentation. Although a natural part of the water cycle, runoff,
erosion and sedimentation have been artificially accelerated by the way humans have chosen to
develop land, leading to pollution.
Almost all nonpoint source pollution is caused by stormwater runoff and erosion. Leaky septic
systems are also considered nonpoint sources. Rainwater and melting snow run over residential
lawns, construction projects, streets and farm fields, picking up pollutants such as soil particles,
chemicals and nutrients and carrying them into nearby water bodies. Nonpoint source pollution
also occurs from infiltration of pollutants into the ground. Pollutants originating from landfills,
abandoned mines, underground storage tanks and septic tanks are possible groundwater pollution
sources.
Lake and Watershed Management
A watershed is that area of land that drains directly into a lake, either through rivers, streams,
surface runoff, or groundwater. A watershed is best envisioned as a funnel with a glass at the
bottom representing a lake. Anything that falls into the funnel will find its way into the glass.
Much the same occurs in a watershed; therefore watershed characteristics such as size, land use,
slope, and soils play an important role in determining both the quality and quantity of the water
that drains to a lake. For this reason, getting to know a lake’s watershed and the activities that go
on in the watershed are of primary concern to the individuals that manage and enjoy the lake.
Lake management refers to the practice of maintaining lake quality such that attainable lake uses
can be achieved (Jones et. al, 2001). Management of a lake is integrally related to management
of the surrounding watershed. Watershed management is the process of protecting the lakes,
streams, and wetlands in the watershed from point and nonpoint source pollution. It is
accomplished by developing an understanding of key factors that affect the water quality of
lakes, streams and wetlands and by following a plan of action to prevent, reduce, or minimize
those activities within a watershed that may negatively impact water quality. Watershed
management consists of many diverse activities including controlling point and nonpoint source
pollution, monitoring water quality, adopting ordinances and policies, educating stakeholders,
and controlling growth and development in a watershed.
Lake Protection and Restoration
Depending on the physical traits of the lake and watershed, and the quality of the incoming
water, certain lakes are suited for particular uses. It can sometimes be difficult to manage a lake
for conflicting uses; for example, trout fishing and motorboat racing. A lake cannot be all things
to all people, and it can be difficult and expensive to force a lake to support a specific use when
it is unrealistic to do so. It is important, therefore, when undergoing a lake protection or
restoration project, to set specific goals that are based on a thorough investigation of the lake and
its watershed. Lake protection is defined as “The act of preventing degradation or deterioration
of attainable lake uses.” Lake protection projects are usually undertaken by municipalities or lake
associations who fear their lake will suffer from the adverse effects of encroaching development.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
7
F. X. Browne, Inc.
Lake restoration refers to the act of bringing a lake back to its attainable uses (Jones, et. al.,
2001). It is important to be realistic in one’s expectations for lake restoration. Nonpoint sources
of pollution in a watershed can be difficult to detect and control, and without proper watershed
management, lake restoration efforts can fail. A comprehensive watershed management plan
should be designed and implemented involving as many watershed stakeholders as possible for
best success in lake restoration projects. In any lake project, educating watershed citizens about
how their activities affect the lake can be extremely helpful.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
8
F. X. Browne, Inc.
3.0
Lake and Watershed Characteristics
3.1
Lake Characteristics
Lake Carey has a surface area 183 acres and the pond just south of the lake has an area of 71
acres. The 3,919 acres watershed for both water bodies is located in Tunkhannock and Lemon
Townships, Wyoming County, PA (see Figure 3.1). The lake has a mean depth of 18.4 feet while
the pond has a mean depth of 3.0 feet. There are two major tributaries to Lake Carey – Meade
Brook and an unnamed tributary that drains Bartron Pond, Mud Pond, and the western portion of
the watershed. Additionally, there are several small unnamed tributaries that drain directly into
the lake and pond. Water exits the lake by evaporation and through an outlet along the
southeastern edge of the pond. The morphometric and hydrologic characteristics of Lake Carey
are summarized in Table 3.1.
Table 3.1
Morphometric and Hydrologic Characteristics of Lake Carey
Total Areas within Watershed
Boundary
4,173 Acres
Watershed Land Surface Area
3,919 Acres
Drainage Basin Area to Lake Surface
Area Ratio
16.3 : 1
Lake Carey
Pond
183 acres
71 acres
Lake Volume
5,414,000 cubic yards
338,431 cubic yards
Sediment Volume
1,203,021 cubic yards
291,200 cubic yards
18.4 feet
3.0 feet
Lake Surface Area
Average Depth
3.2
Uses of Lake Carey
3.2.1
Present Uses
Lake Carey is used for a variety of activities including fishing, boating, swimming, and ice
skating. As a valued recreational area, Lake Carey promotes the local economy; therefore,
protecting the water quality is important not only from a natural and aesthetic perspective, but
from an economic perspective as well.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
9
F. X. Browne, Inc.
0
0.2
0.4
0.8
1.2
Miles
Figure 3.1 Lake Carey Watershed Boundary
Data Source: USGS 7.5 min. Quadrangle Series, Springville and Tunkhannock, PA
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
10
F. X. Browne, Inc.
3.2.2
Impairment of Recreational Uses
The water quality in Lake Carey has severely deteriorated over the years due to excessive
nutrient and sediment input from the lake’s watershed. In recent years, the lake has become
eutrophic to hyper-eutrophic. The lake is plagued with blooms of the blue-green algae,
Aphanizomenon, a bluegreen algae which is very resistant to chemical treatment. The eutrophic
conditions are deleterious to the aesthetic value of the lake. Extremely low dissolved oxygen
concentrations in the bottom waters leads to internal release of nutrients from the sediments as
well as negatively impacting fish habitat. During the summer, excessive algal growth causes a
reduction in transparency. The lack of water clarity has led many residents to complain about the
aesthetics of the lake. In addition, the reported increase in aquatic plant growth in some areas of
the lake has led to complaints about the quality of the fishing and boating.
3.3
Watershed Characteristics
3.3.1
Geology and Topography
The Lake Carey watershed is located within the North Central Appalachian Ecoregion and just
outside of the Ridge and Valley Ecoregion. The North Central Appalachians Ecoregion is part of
a vast, elevated plateau composed of horizontally bedded sandstone, shale, siltstone,
conglomerate, and coal. The Ridge and Valley Ecoregion extends from Wayne County,
Pennsylvania, through Virginia along a southwesterly axis. It is characterized by alternating
forested ridges and agricultural valleys that are elongated and folded and faulted. As a result of
extreme folding and faulting events, the region's roughly parallel ridges and valleys have a
variety of widths, heights, and geologic materials, including limestone, dolomite, shale, siltstone,
sandstone, chert, mudstone, and marble. Springs and caves are relatively numerous. The
ecoregion has a diversity of habitats.
The Catskill continental group underlies glacial drift throughout about 95 percent of Wyoming
County, including the Lake Carey watershed. The area around Lake Carey consists of rolling
hills. The elevation of the watershed varies from 1490 to 947 feet above sea level. Lake Carey is
at an elevation of 947 feet above sea level. Some areas of the Lake Carey watershed have very
steep slopes, up to 25 percent. Although the areas of steeper watershed slopes most likely
contribute to runoff and associated sediment and nutrient problems in this watershed, the
agricultural development and poor rural road construction are a greater soil erosion problem.
3.3.2
Soils
As shown in Table 3.2, the Lake Carey watershed consists of 16 major soil series with 66
different soil types. All of the soils in the watershed are rated as “severe” for conventional septic
systems due to a seasonably high water table and low percolation rates. However, some soils in
the watershed are acceptable for elevated sand mounds, spray irrigation systems, or drip
irrigation systems. Figure 3.2 shows the distribution and location of each soil type within the
watershed. Most of the soils within the Lake Carey Watershed have a low risk of erosion. Figure
3.3 shows that the erosion hazard all soil within the watershed is rated as either slight or
moderate.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
11
F. X. Browne, Inc.
Table 3.2
Lake Carey Soils
Soil Name
Soil
Code
Erosion
Hazard
Arnot very channery silt loam
Arnot-Rock outcrop complex
Arnot-Rock outcrop complex
Arnot-Rock outcrop complex, steep
Atherton loam
Bath channery silt loam
Bath channery silt loam
Bath channery silt loam
Bath extremely stony silt loam
Bath extremely stony silt loam
Braceville gravelly loam
Holly silt loam
Lackawanna channery loam
Lackawanna channery loam
Lackawanna channery loam
Lackawanna extremely stony loam
Lackawanna extremely stony loam
Lackawanna and Bath extremely stony loam
Lordstown channery silt loam
Lordstown channery silt loam
Lordstown channery silt loam
Lordstown flaggy silt loam
Lordstown flaggy silt loam
Lordstown extremely stony silt loam
Lordstown extremely stony silt loam
Mardin channery silt loam
Mardin channery silt loam
Mardin channery silt loam
Mardin flaggy silt loam
Mardin flaggy silt loam
Mardin extremely stony silt loam
Mardin extremely stony silt loam
Medisaprists and Medihemists
Morris channery loam
Morris channery loam
Morris channery loam
Morris flaggy loam
Morris extremely stony loam
Morris extremely stony loam
Norwich and Chippewa channery silt loams
Norwich and Chippewa channery silt loams
ArC
AsB
AsD
ASE
At
BaB
BaC
BaD
BbB
BbD
BcB
Hm
LaB
LaC
LaD
LbB
LbD
LCE
LeB
LeC
LeD
LfB
LfC
LxB
LxD
McB
McC
McD
MfB
MfC
MhB
MhD
MK
MrA
MrB
MrC
MsB
MxB
MxD
NcA
NcB
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
slight
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
Septic
System
Rating
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
Depth
To
Ground water (ft)
> 6.0
> 6.0
> 6.0
> 6.0
0 - 0.5
3.0 - 6.0
3.0 - 6.0
3.0 - 6.0
3.0 - 6.0
3.0 - 6.0
1.5 - 3.0
0 - 0.5
3.0 - 6.0
3.0 - 6.0
3.0 - 6.0
3.0 - 6.0
3.0 - 6.0
3.0 - 6.0
> 6.0
> 6.0
> 6.0
> 6.0
> 6.0
> 6.0
> 6.0
1.5 - 3.0
1.5 - 3.0
1.5 - 3.0
1.5 - 3.0
1.5 - 3.0
1.5 - 3.0
1.5 - 3.0
NA
0.5 - 1.5
0.5 - 1.5
0.5 - 1.5
0.5 - 1.5
0.5 - 1.5
0.5 - 1.5
0.0 - 0.5
0.0 - 0.5
PA1590-01-001
12
F. X. Browne, Inc.
Table 3.2
Lake Carey Soils (Continued)
Soil Name
Soil
Code
Norwich and Chippewa extremely stony silt loams
Oquaga channery loam
Oquaga channery loam
Oquaga channery loam
Oquaga flaggy loam
Oquaga flaggy loam
Oquaga extremely stony loam
Oquaga extremely stony loam
Oquaga and Lordstown extremely stony loams
Rexford loam
Urban land
Volusia channery silt loam
Volusia channery silt loam
Volusia channery silt loam
Volusia flaggy silt loam
Volusia flaggy silt loam
Volusia extremely stony silt loam
Wellsboro channery loam
Wellsboro channery loam
Wellsboro channery loam
Wellsboro flaggy loam
Wellsboro flaggy loam
Wellsboro extremely stony loam
Wellsboro extremely stony loam
Wurtsboro channery loam
NxB
OcB
OcC
OcD
OfB
OfC
OxB
OxD
OYE
ReA
Ur
VcA
VcB
VcC
VfB
VfC
VxB
WcB
WcC
WcD
WfB
WfC
WgB
WgD
WkB
Erosion
Hazard
slight
slight
slight
slight
slight
slight
slight
slight
moderate
slight
slight
slight
slight
slight
slight
slight
moderate
slight
slight
slight
slight
slight
slight
slight
slight
Septic
System
Rating
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
severe
Depth
To
Groundwater (ft)
0.0 - 0.5
> 6.0
> 6.0
> 6.0
> 6.0
> 6.0
> 6.0
> 6.0
> 6.0
0.5 - 1.5
> 6.0
0.5 - 1.5
0.5 - 1.5
0.5 - 1.5
0.5 - 1.5
0.5 - 1.5
0.5 - 1.5
1.5 - 3.0
1.5 - 3.0
1.5 - 3.0
1.5 - 3.0
1.5 - 3.0
1.5 - 3.0
1.5 - 3.0
1.5 - 3.0
Note: The soil information is from the Lackawanna and Wyoming Counties Soil Survey, issued in March 1982.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
13
F. X. Browne, Inc.
Figure 3.2 Soils in the Lake Carey Watershed
Data Source: Soil Survey of Lackawanna and Wyoming Counties, PA, issued in March 1982.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
14
F. X. Browne, Inc.
Figure 3.3 Soil Erosion Hazard in the Lake Carey Watershed
Data Source: Soil Survey of Lackawanna and Wyoming Counties, PA, issued in March 1982.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
15
F. X. Browne, Inc.
3.3.3
Land Uses
The banks of Lake Carey are protected by forested areas to the north, but most of the lake is
surrounded by year-round and seasonal homes that use septic systems for wastewater disposal
with little vegetative buffer between the homes and the lake. As shown in Figure 3.4 and Table
3.3, only about 5 percent of the Lake Carey watershed is developed but most of the developed
area is concentrated around the lake and pond. The majority of the watershed is either forested or
agricultural land. A significant number of agricultural best management practices have been
installed in the Lake Carey watershed in recent years. The effectiveness of these BMPs has not
been specifically evaluated; however, pollutant loadings from agricultural lands are likely still a
significant source of nonpoint source pollution in the watershed.
Table 3.3
Land Use in Lake Carey Watershed (not including Lake Carey)
Land Use Category
Area (acres)
Percentage
Agriculture
1,788
46
Forested
1,828
46
Open Water
102
3
Residential
201
5
Totals
3,919
100
Data Source: Wyoming County Planning Commission and aerial photographs .
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
16
F. X. Browne, Inc.
Figure 3.4 Land Uses in the Lake Carey Watershed
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
17
F. X. Browne, Inc.
4.0
Water Quality Monitoring Program
A water quality monitoring program for Lake Carey was designed and implemented to obtain
relevant data to accurately assess the ecological condition of the lake and to provide relevant
information for the development of a realistic pollutant budget for Lake Carey. The monitoring
program included lake and pond biological and chemical testing, sediment testing, stream
testing, and well testing. In addition, special studies, including algal assay tests and alum studies,
were performed as part of this study to provide necessary information to recommend appropriate
lake management alternatives.
4.1
Lake and Pond Monitoring
Lake Carey and the pond just south of Lake Carey were monitored by volunteers of the Lake
Carey Cottages Association during the summers of 2003 and 2004. F. X. Browne, Inc. trained
volunteers to collect samples from the surface and bottom of each water body. The volunteers
were also trained to collect phytoplankton and zooplankton samples and chlorophyll a samples.
Samples that were collected during 2003 were delivered to the Wilkes University laboratory for
chemical analysis. F. X. Browne, Inc. analyzed samples for chlorophyll a, and Dr. Kenneth
Wagner identified phytoplankton and zooplankton species in all samples. Additional lake and
pond samples were collected during the summer of 2004 and analyzed at the F. X. Browne, Inc.
laboratory. Algal assay tests were conducted once during 2003 and once during 2004 on both
lake and pond water collected by volunteers. F. X. Browne, Inc. collected sediment samples in
Lake Carey at six separate sampling locations. The locations of lake and pond sampling sites are
provided in Figure 4.1.
4.1.1
Monitoring Methodology
Water samples from the lake and pond were collected using a horizontal Van Dorn water
sampler. Water chemistry samples were collected at 0.5 meter below the water surface and 0.5
meters above the bottom of the lake and pond. In addition, dissolved oxygen and temperature
profiles were measured and Secchi disk readings were taken at the lake and pond on each
sampling date. Zooplankton samples were collected by towing a plankton net through the water
column.
TSS
The concentration of total suspended solids in a lake is a measure of the amount of particulate
matter in the water column. Suspended solids are comprised of both organic matter (i.e. algae,
bacteria, detritus) and inorganic materials (i.e. soil and clay particles). In most lakes, total
suspended solids concentrations are less than 25 mg/L and can often be less than 10 mg/L. Lakes
that receive significant amounts of erosion from stormwater runoff and those with high
phytoplankton biomass usually have high total suspended solids concentrations.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
18
F. X. Browne, Inc.
1
2
3
4
5
6
Sediment Site
Sediment Site, Algal Assay,
Lake Chemistry Site
Sediment Site
Sediment Site
Sediment Site
Sediment Site, Algal Assay,
Pond Chemistry Site
Figure 4.1 Lake and Pond Sampling Locations
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
19
F. X. Browne, Inc.
pH
In lake ecosystems, changes in pH occur when phytoplankton use carbon dioxide during
photosynthesis. Dissolved carbon dioxide reacts with water to form carbonic acid (H2CO3).
When phytoplankton take up the carbon dioxide dissolved in the lake water during
photosynthesis, it results in a decrease in the carbonic acid concentration and a consequent
increase in pH. For this reason, the pH of surface waters is higher during an algal bloom than the
pH of bottom water where phytoplankton (suspended microscopic plants) numbers are much
lower.
Phosphorus
Phosphorus and nitrogen compounds are major nutrients required for growth of algae and
macrophytes in lakes. The dissolved inorganic nutrients, dissolved reactive phosphorus, nitrate
nitrogen, and ammonia nitrogen are regarded as the forms most readily available to support
aquatic growth. In most lake systems, phosphorus is the limiting nutrient and therefore is the
nutrient that usually controls the amount of aquatic plant growth (vascular plants and algae).
Total phosphorus represents the sum of all phosphorus forms, and includes dissolved and
particulate organic phosphates from algae and other organisms, inorganic particulate phosphorus
from soil particulates and other solids, polyphosphates from detergents, and dissolved
orthophosphates. Soluble orthophosphates is the phosphorus form that is most readily available
for algal uptake and is usually reported as dissolved reactive phosphorus, because the analysis
takes place under acid conditions that can result in some hydrolysis of other phosphorus forms.
Total phosphorus levels are strongly affected by the daily phosphorus loads that enter the lake.
Soluble orthophosphates levels, however, are affected by algal consumption during the growing
season.
Nitrogen
Nitrogen compounds are also important for algae and aquatic macrophyte growth. The common
inorganic forms of nitrogen in water are nitrate (N03), nitrite (N02), and ammonia (NH3). The
form of inorganic nitrogen present depends largely on dissolved oxygen concentrations. Nitrate
is the form usually found in surface waters, while ammonia is only stable under low oxygen
conditions. Nitrite is an intermediate form of nitrogen that is unstable in surface waters. Nitrate
and nitrite (total oxidized nitrogen) are often analyzed together and reported as N03+N02-N,
although nitrite concentrations are usually insignificant. Total Kjeldahl nitrogen (TKN)
concentrations include ammonia and organic nitrogen (both soluble and particulate forms).
Organic nitrogen is easily determined by subtracting ammonia nitrogen from total Kjeldahl
nitrogen. Total nitrogen is calculated by summing the nitrate-nitrite, ammonia, and organic
nitrogen fractions together.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
20
F. X. Browne, Inc.
Transparency
The transparency of the water was measured in each of the lakes using a Secchi disk. Secchi disk
transparency is an indirect measurement of the total amount of organic and inorganic turbidity in
a lake that is measured using a 20 cm white and black
patterned disk. The Secchi disk is lowered into the water until
it is no longer visible, and then raised slightly until it can just
be seen. The Secchi disk transparency is the depth in meters
recorded at that point. Observed Secchi disk values can range
from a few centimeters in very turbid lakes to over 40 meters
in the clearest known lakes. Although somewhat simplistic
and subjective, this testing method probably best represents
the conditions that are most readily visible to the common
lake user. Secchi disk measurements were taken at the
deepest point in the lake on each sampling event.
Secchi disk transparency is related to the transmission of
light in water and depends on both the absorption and scattering of light. The absorption of light
in dark-colored waters reduces light transmission. Light scattering is usually a more important
factor than absorption in determining Secchi depths. Scattering can be caused by color, by
particulate organic matter, including algal cells, and by inorganic materials such as suspended
clay particles in water. Water transparency is widely used to classify the trophic state of a lake.
Chlorophyll a
Samples were collected for chlorophyll a analysis in each lake. A sample was collected from the
photic zone of each lake using a Van Dorn sampler. The photic zone is the portion of the water
column that receives enough light for the photosynthetic process to occur and for algae to live.
The photic zone is considered to extend from the water surface to a depth that is two times the
Secchi disk transparency. The water sample from each lake was transferred to opaque bottles,
transported to the F. X. Browne, Inc. lab in Marshalls Creek, and treated to extract chlorophyll a
from algae cells for analysis and determination of the chlorophyll a concentration. Chlorophyll a
is the green pigment that all green plants use to convert sunlight to chemical energy during
photosynthesis. Chlorophyll a constitutes about one to two percent of the dry weight of
planktonic algae, so the amount of chlorophyll a in a water sample can be used as an indicator of
phytoplankton (algae) biomass.
Phytoplankton and Zooplankton
Phytoplankton samples were collected at each lake by obtaining a water sample from the lake
photic zone. Phytoplankton are microscopic algae that have little or no resistance to currents and
are found free floating and suspended in open water. Their forms may be unicellular, colonial, or
filamentous. As photosynthetic organisms (primary producers), phytoplankton form the
foundation of the aquatic food web and are grazed upon by zooplankton (microscopic animals)
and herbivorous, or plant-eating, fish.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
21
F. X. Browne, Inc.
A healthy lake should support a diverse assemblage of phytoplankton represented by a variety of
algal species. Excessive phytoplanktonic growth, which typically consists of a few dominant
species, is undesirable. Excessive growth can result in severe oxygen depletion in the water at
night, when the algae are respiring (using up oxygen) and not photosynthesizing (producing
oxygen). Oxygen depletion can also occur following an algal bloom when bacteria grow and
multiply using dead algal cells as a food source. Excessive growth of some species of algae,
particularly members of the blue-green group, may cause taste and odor problems, release toxic
substances into the water, or give the water an unattractive green soupy or scummy appearance.
Planktonic productivity is commonly expressed by enumeration and biomass. Enumeration of
phytoplankton is expressed as cells per milliliter (cells/mL). Biomass is expressed on a mass per
volume basis as micrograms per liter (g/L). Of the two, biomass provides a better estimate of
the actual standing crop of phytoplankton in lakes.
What was previously referred to as blue-green algae (Cyanophyta) is now commonly referred to
in the scientific literature as Cyanobacteria. Cyanobacteria are organisms that act like both algae,
in that they contain chlorophyll and perform photosynthesis, and bacteria, in that their cell
structure is similar to bacteria. In this report we refer to these organisms as blue-green algae from
the taxa Cyanophyta since their primary role in lakes are similar to algae.
It should be noted that since phytoplankton populations tend to wax and wane throughout the
year, a single sample from a lake or pond may not be indicative of the overall status of the lake
with respect to algae. For example, the lake could show only a small amount of algae on one
sampling date, and due to weather conditions or other factors, an algae bloom could occur the
next week. Similarly, the lake may be sampled during an algae bloom, and the phytoplankton
populations may be low at other times of the year. July and August are typically the months of
the year when algae populations are highest, so sampling during July probably provides a fairly
good indication of the maximum growing season algae populations.
Zooplankton are microscopic animals whose movements in a lake are primarily dependent upon
water currents. Zooplankton remain suspended in open water. Major groups of zooplankton
include protozoa, rotifers and crustaceans. Crustaceans are further divided into copepods and
cladocerans (i.e. water fleas). Zooplankton are generally smaller than two millimeters (one-tenth
of an inch) in size and primarily feed on algae, other zooplankton, and plant and animal particles.
Zooplankton grazing can have a significant impact on phytoplankton species composition and
productivity (i.e. biomass) through selective grazing (e.g. size of zooplankton influences what
size phytoplankton are consumed) and nutrient recycling. Zooplankton, in turn, are consumed by
fish, waterfowl, aquatic insects, and others, thereby playing a vital role in the transfer of energy
from phytoplankton to higher trophic levels.
A minimum of two discrete lake water samples were collected from the photic zone of each lake
using a horizontal Van Dorn water sampler. The photic zone was defined in this study as a water
depth equal to two times the Secchi disk depth. Photic zone discrete samples were then
composited together and analyzed for chlorophyll a and used for phytoplankton identification
and enumeration. Zooplankton samples were collected by vertically towing a plankton net (80
µm mesh size with an 8-inch orifice) at least two times through the water column. Both
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
22
F. X. Browne, Inc.
phytoplankton and zooplankton identification and enumeration were performed in the laboratory
using a Sedgewick-Rafter counting chamber and a microscope equipped with a Whipple Grid.
All phytoplankton and zooplankton cell densities (number per volume) were expressed as
biomass based on mean cell size.
Dissolved Oxygen and Temperature
Dissolved oxygen and temperature measurements were taken from the entire water column in the
lake using a YSI 610DM dissolved oxygen and temperature meter. Measurements were collected
at approximately half-meter intervals.
In late spring or the beginning of summer, deep temperate lakes develop stratified layers of
water, with warmer water near the lake's surface (epilimnion) and colder water near the lake's
bottom (hypolimnion). As the temperature difference becomes greater between these two water
layers, the resistance to mixing increases. Under these circumstances, the epilimnion (top water)
is usually oxygen-rich due to photosynthesis and direct inputs from the atmosphere, while the
hypolimnion (bottom water) may become depleted of oxygen due to consumption by organisms
decomposing organic matter at the lake bottom.
Conversely, shallow temperate lakes may never develop stratified layers of water. For these
shallow lake systems, wave action caused by the wind may be sufficient to keep the entire lake
completely mixed for most of the year. In shallow lakes, low dissolved oxygen concentrations
may occur above the lake sediments even though most of the water in the lake is completely
mixed. Therefore, both shallow and deep temperate lakes can have low dissolved oxygen
concentrations near the surface of the lake sediments. If low dissolved oxygen levels occur near
the lake bottom, sediments may release significant amounts of nutrients (primarily
orthophosphorus and ammonia) back into the lake, thereby contributing more nutrients for algae
and aquatic plant growth.
4.1.2
Lake and Pond Water Quality Results
Temperature and Dissolved Oxygen
Lake Carey was thermally stratified from May through August at the lake during 2003 and 2004.
During the period of stratification, the thermocline occurred at a depth of approximately 4 to 5
meters throughout the growing season. Temperatures within the warm, upper layer (epilimnion)
ranged from 14.1ºC (57ºF) in May 2003 to 25.5ºC (78ºF) in August 2003. Temperatures in the
cold, lower layer (hypolimnion) ranged from 8.8ºC (48ºF) to 10.7ºC (51ºF) during the 2003
growing season. Temperatures showed a similar pattern in 2004, except that the June
temperatures were warmer and the lake was more strongly stratified in June 2004 than in June
2003. This may have been due to the heavy rains during June 2003 which cooled the water.
Dissolved oxygen concentrations in the hypolimnion at the lake were depleted by microbial
activity to levels below 2 mg/L during the entire growing season during 2003 and during June of
2004. The bottom 2 to 5 meters of the hypolimnion remained completely anoxic (without
oxygen) throughout June, July, and August at the lake station. The anoxia occurred to a slightly
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
23
F. X. Browne, Inc.
lesser extent during May of 2004, but dissolved oxygen concentrations reached completely
anoxic levels below 4.0 meters during June 2004.
The pond at Lake Carey was not thermally stratified during either 2003 or 2004, with the
exception of very weak stratification during July 2003. Temperatures ranged from 14.0ºC (57ºF)
at the bottom during May 2003 to 26.4ºC (80ºF) at the surface during July 2003. During 2004,
the June temperatures were warmer than the June 2003 temperatures. Dissolved oxygen
concentrations reached zero at the bottom of the pond during June and August 2003, but the
majority of the water column remained well oxygenated during the remainder of the study
period. Dissolved oxygen and temperature profile data for Lake Carey are presented in Appendix
B. Growing season dissolved oxygen profiles at the lake and pond stations during 2003 and 2004
are presented graphically in Figures 4.2 through 4.8.
Coldwater fish such as trout, walleye, and northern pike function best at temperatures below
22ºC (71.6ºF) and dissolved oxygen levels above 5.0 mg/L. During the summer stratification
period, these fish probably experienced some stress in the lake as surface water temperatures
warmed and bottom water dissolved oxygen concentrations declined. Coldwater fish most likely
found refuge around cold springs near shore and at the bottom of the epilimnion in open water.
The bottom of the epilimnion is a desirable location for coldwater fish because temperatures are
cooler than at the surface while dissolved oxygen concentrations are still high enough to allow
life-sustaining activities. Pond water temperatures generally remained too warm during the
growing season for coldwater fish survival.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
24
F. X. Browne, Inc.
Lake Carey - Lake
2003 Dissolved Oxygen Profiles
0
2
4
6
8
10
12
14
May 14
June 8
July 26
August 23
1
0
0
3
1
6
2
6
8
10
12
14
16
18
20
22
24
26
28
30
3
6
2
9
9
3
3
12
12
4
Depth (m)
4
Depth (ft)
Depth (m)
0
15
5
15
5
18
Depth (ft)
0
Lake Carey - Lake
2003 Temperature Profiles
18
6
6
21
21
7
7
24
24
8
8
27
9
9
30
0
2
4
6
8
10
12
May 14
June 8
July 26
August 23
14
27
30
6
8
10
12
14
Dissolved Oxygen (mg/L)
16
18
20
22
24
26
28
30
Temperature (ºC)
Figure 4.2 Dissolved oxygen profiles at Lake Figure 4.3 Temperature profiles at Lake
Carey lake station during 2003
Carey lake station during 2003
Lake Carey -Lake
2004 Dissolved Oxygen Profiles
0
2
4
6
8
10
12
May 3
June 23
1
6
0
0
3
1
6
2
8
10
12
14
16
18
20
22
24
0
May 3
June 23
3
6
2
9
9
3
3
12
Depth (m)
15
5
Depth (ft)
Depth (m)
12
4
4
15
5
Depth (ft)
0
Lake Carey - Lake
2004 Temperature Profiles
18
18
6
6
21
21
7
7
24
24
8
8
27
27
9
9
0
2
4
6
8
10
6
12
8
10
12
14
16
18
20
22
24
Temperature (ºC)
Dissolved Oxygen (mg/L)
Figure 4.4 Dissolved oxygen profiles at Figure 4.5 Temperature profiles at Lake
Lake Carey lake station during 2004
Carey lake station during 2004
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
25
F. X. Browne, Inc.
Lake Carey - Pond
2003 Dissolved Oxygen Profiles
0
2
4
6
8
10
12
14
May 14
June 8
July 26
August 23
0.2
0
0.0
10
12
14
16
18
20
22
24
26
28
30
May 14
June 8
July 26
August 23
0.2
1
0.4
0
1
0.4
0.6
0.6
2
2
0.8
Depth (ft)
3
1.0
1.2
Depth (m)
0.8
Depth (m)
8
3
1.0
1.2
4
1.4
Depth (ft)
0.0
Lake Carey - Pond
2003 Temperature Profiles
4
1.4
5
5
1.6
1.6
1.8
1.8
6
2.0
6
2.0
0
2
4
6
8
10
12
14
8
10
12
14
16
18
20
22
24
26
28
30
Temperature (ºC)
Dissolved Oxygen (mg/L)
Figure 4.6 Dissolved oxygen profiles at Figure 4.7 Temperature profiles at Lake
Lake Carey pond station during 2003
Carey pond station during 2003
Lake Carey Dissolved Oxygen/Temperature Profiles
Pond Station - 2004
Temperature (ºC)
0
3
6
9
12
15
18
21
24
27
0.0
0
Dissolved Oxygen - June
Temperature - June
0.2
1
0.4
0.6
2
3
1.0
1.2
Depth (ft)
Depth (m)
0.8
4
1.4
5
1.6
1.8
6
2.0
0
3
6
9
12
15
18
21
24
27
Dissolved Oxygen (mg/L)
Figure 4.8 Dissolved oxygen and temperature profiles at Lake Carey pond station
during 2004
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
26
F. X. Browne, Inc.
Alkalinity
Alkalinity is a measure of the buffering capacity or acid-neutralizing capability of water. As
alkalinity increases, the ability of the water to neutralize acid also increases. Alkalinity is
equivalent to the concentration of bicarbonate ions and is usually expressed in terms of calcium
carbonate (CaCO3) concentration. In well-buffered lakes, alkalinity values are 100 mg/L as
CaCO3. Lakes with low buffering capacity have alkalinity values less than 10 mg/L as CaCO3.
Many lakes in the northeastern United States fall into this category. These lakes are susceptible
to acid precipitation and may be acidic year-round or subject to spring acidification due to
snowmelt runoff.
Alkalinity was measured in the surface and bottom waters at both the lake and pond at Lake
Carey during 2003. Alkalinity was not monitored during 2004. During the 2003 growing season,
surface alkalinity varied between 17 mg/L and 36 mg/L as CaCO3 at the lake, and 17 mg/L and
40mg/L at the pond station. Alkalinity concentrations at the bottom waters of the pond ranged
from 17 to 33 mg/L. The bottom water alkalinity readings were higher at the lake ranging from
30 to 69 mg/L. While these results show that Lake Carey has a relatively low buffering capacity,
the water has enough buffering ability to prevent aquatic life from being subjected to stress
caused by acidic conditions.
Total Suspended Solids and Water Transparency
The total suspended solids in a water sample refer to the total weight of all the organic and
inorganic particulate matter found in the sample. When measured in lakes, total suspended solids
include all particulate matter found suspended in the water column. In most lakes, total
suspended solids concentrations are less than 25 mg/L and can often be less than 10 mg/L. Lakes
that receive significant amounts of sediment from stormwater runoff and those with high
phytoplankton biomass usually have high total suspended solids concentrations.
During the 2003 growing season, total suspended solids in Lake Carey were low at both the
surface and the bottom waters in the lake. At the lake surface, the total suspended solids
concentrations ranged from 1.1 mg/L to 5.5 mg/L with an average value of 3.2 mg/L. At the lake
bottom, the total suspended solids concentrations ranged from 1.4 to 6.5 with an average value of
4.2 mg/L. In the pond, total suspended solids concentrations were higher than in the lake,
although similar in both the top and bottom layers. Total suspended solids concentrations in the
pond ranged between 3.0 and 13.3 mg/L at the surface with an average value of 9.3 mg/L. At the
pond bottom, total suspended solids concentrations ranged from 3.0 to 16.6 mg/L with an
average value of 11.0 mg/L. Total suspended solids were not monitored during 2004.
The Secchi disk transparency at the Lake Carey lake station during the 2003 growing season
ranged from 1.0 to 4.5 meters with an average transparency of 2.4 meters. The transparency at
the Lake Carey pond during 2003 ranged between 0.7 to 1.3 meters with an average transparency
of 0.9 meters. The lower transparencies occurred during July and August when blue-green algae
blooms were more prevalent. The 2003 Secchi disk transparency values for the both the Lake
Carey lake and pond are presented graphically in Figure 4.9.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
27
F. X. Browne, Inc.
The Lake Carey growing season transparencies were slightly lower (less favorable) at both
stations during 2004 than during 2003. The 2004 Secchi disk transparency at the Lake Carey lake
station ranged from 1.2 to 1.7 meters with an average transparency of 1.4 meters. The
transparency at the Lake Carey pond station during 2004 ranged between 0.55 to 1.0 meters with
an average transparency of 0.78 meters. The lowest transparencies occurred during 2004. The
2004 Secchi disk transparency values for the both the Lake Carey lake and pond stations are
presented graphically in Figure 4.10.
Lake Carey 2003
Secchi Disk Transparency
5.0
Lake
Pond
4.5
Secchi Disk Transparency (m)
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
May-03
Jun-03
Jul-03
Aug-03
Figure 4.9 Secchi disk transparency at Lake Carey during 2003
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
28
F. X. Browne, Inc.
Lake Carey 2004
Secchi Disk Transparency
5.0
Lake
Pond
4.5
Secchi Disk Transparency (m)
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
May-04
Jun-04
Jul-04
Aug-04
Figure 4.10 Secchi disk transparency at Lake Carey during 2004
Phosphorus
The trophic state of a lake is largely dependent upon nutrient levels in the water column.
Phosphorus and nitrogen are two nutrients that are essential for phytoplankton growth. During
the Lake Carey study, several fractions of phosphorus were monitored including soluble, or
dissolved, reactive phosphorus (DRP, also called SRP or filtered orthophosphate) and total
unfiltered phosphorus. Phosphorus is often the limiting nutrient in most freshwater systems.
Because of the importance of phosphorus with respect to phytoplankton growth, phosphorus is
usually the nutrient targeted by lake managers for reduction. Often phosphorus reduction is the
goal of many lake managers overseeing lakes that are not phosphorus limited, because
phosphorus is an easier input to control than nitrogen.
It is important to examine nutrient concentrations with a focus on the phytoplankton growing
season (May through September), since phytoplankton growth rates are highest during this time.
The phytoplankton growing season in Lake Carey also corresponds to the period of highest
recreational activity at the lake. Therefore, the perception of the general health of Lake Carey by
its users is formed during this season.
Total unfiltered phosphorus concentrations (referred to as total phosphorus in this report)
measured in the surface waters during 2003 were higher at the pond than the lake, as illustrated
in Figure 4.11. However, concentrations were fairly high at both stations. The average growing
season total phosphorus surface concentration at the lake was 0.072 mg/L. At the pond, the
growing season average was 0.193 mg/L. The highest total phosphorus concentrations occurred
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
29
F. X. Browne, Inc.
Lake Carey 2003
Surface Phosphorus Concentrations
0.400
TP-Lake
OP-Lake
TP-Pond
OP-Pond
0.350
Phosphorus (mg/L)
0.300
0.250
0.200
0.150
0.100
0.050
0.000
May-03
Jun-03
Jul-03
Aug-03
Figure 4.11 Surface phosphorus concentrations at Lake Carey during 2003
Lake Carey 2004
Surface Phosphorus Concentrations
0.400
TP-Lake
OP-Lake
TP-Pond
OP-Pond
0.350
Phosphorus (mg/L)
0.300
0.250
0.200
0.150
0.100
0.050
0.000
May-04
Jun-04
Jul-04
Aug-04
Figure 4.12 Surface phosphorus concentrations at Lake Carey during 2004
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
30
F. X. Browne, Inc.
during July and August 2003 at both the lake and pond. During 2004, the total phosphorus
concentrations were somewhat lower in the surface waters than 2003 concentrations, averaging
0.044 mg/L at the lake station and 0.143 mg/L at the pond station. The 2004 surface phosphorus
concentrations are shown in Figure 4.12. Nutrient data are provided in Appendix C.
Total phosphorus concentrations at Lake Carey were significantly higher in the hypolimnion than
in the surface waters at both the lake and pond during 2003, as shown in Figure 4.13. This was
especially the case at the lake. The average growing season hypolimnetic total phosphorus
concentrations were 0.880 mg/L at the lake and 0.103 mg/L at the pond. This indicates that
phosphorus was released from the bottom sediments in the lake during the period of
stratification. The maximum growing season hypolimnetic total phosphorus concentration was
excessively high at 1.600 mg/L at the lake in June of 2003. Total phosphorus was not measured
in the hypolimnion at the pond during 2004. The average hypolimnetic total phosphorus at the
lake was 0.345 mg/L, which was lower than the 2003 average value but still very high.
Hypolimnetic total phosphorus concentrations during 2004 are shown in Figure 4.14.
Dissolved reactive phosphorus (DRP, or soluble reactive phosphorus) is the dissolved inorganic
fraction of phosphorus. This is the form most readily available for uptake by phytoplankton.
Surface DRP concentrations at Lake Carey were fairly high during the 2003 growing season,
averaging 0.026 mg/L at the lake and 0.017 mg/L at the pond as shown in Figure 4.11. During
2004, the growing season average surface DRP concentrations were much lower, averaging
0.002 mg/L at the lake and 0.004 mg/L at the pond, as shown in Figure 4.12. This is most likely
due to the fact that the large algae populations in the lake during much of the year consumed
most of the available DRP.
The Lake Carey hypolimnetic DRP concentrations were high at the lake during 2003, averaging
0.934 mg/L, as shown in Figure 4.13. The hypolimnetic DRP concentrations were much lower at
the pond, averaging 0.020 mg/L. This is because phosphorus was released from the sediments
under anoxic conditions in the lake, but since the pond was not thermally stratified, internal
phosphorus release occurred to a much lesser extent. During 2004, hypolimnetic DRP
concentrations averaged 0.255 at the lake, which is extremely high, as shown in Figure 4.14.
Hypolimnetic DRP was not measured at the pond during 2004.
The maximum total phosphorus and DRP concentrations were very high at both the Lake Carey
lake and pond, especially during 2003. 2003 was an extremely wet year and therefore large
nutrient loads most likely entered the lake during the growing season from the surrounding
watershed via stormwater runoff. The U.S. Environmental Protection Agency (US EPA) has
established a classification criterion for total phosphorus concentrations in lakes. According to
this classification, surface total phosphorus concentrations greater than 0.030 mg/L are
considered indicative of eutrophic conditions and surface total phosphorus concentrations greater
than 0.065 mg/L are considered indicative of hypereutrophic conditions. Therefore, according to
the US EPA classification, the Lake Carey pond was considered extremely hyper-eutrophic
during both 2003 and 2004, and the lake was considered eutrophic during 2003 and hypereutrophic during 2004 with respect to total phosphorus concentrations.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
31
F. X. Browne, Inc.
Lake Carey 2003
Hypolimnetic Phosphorus Concentrations
1.800
TP-Lake
OP-Lake
TP-Pond
OP-Pond
1.600
1.400
Phosphorus (mg/L)
1.200
1.000
0.800
0.600
0.400
0.200
0.000
May-03
Jun-03
Jul-03
Aug-03
Figure 4.13 Hypolimnetic phosphorus concentrations at Lake Carey during 2003
Lake Carey 2004
Hypolimnetic Phosphorus Concentrations
1.800
TP-Lake
OP-Lake
1.600
1.400
Phosphorus (mg/L)
1.200
1.000
0.800
0.600
0.400
0.200
0.000
May-04
Jun-04
Jul-04
Aug-04
Figure 4.14 Hypolimnetic phosphorus concentrations at Lake Carey during 2004
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
32
F. X. Browne, Inc.
Nitrogen
The nitrogen fractions analyzed during the Lake Carey study included nitrate/nitrite, ammonia,
and total Kjeldahl nitrogen. Ammonia and nitrate are the forms of nitrogen that are most readily
used by phytoplankton. Some blue-green algae can also use atmospheric nitrogen when ammonia
and nitrate concentrations become low. In addition to ammonia and nitrate, the concentration of
total Kjeldahl nitrogen (TKN) was measured at both the lake and pond during the study period.
The TKN concentration can be used to calculate the amount of organic nitrogen present in the
lake water. The most common sources of nitrogen entering a lake are agricultural runoff,
wastewater, and atmospheric sources such as rainfall, snowfall, and nitrogen gas.
Ammonia concentrations in the epilimnion in Lake Carey were low during 2003 at both the lake
and pond. Nitrogen parameters were not measured at either station during 2004. The 2003
surface ammonia concentrations averaged 0.02 mg/L in the lake and 0.016 mg/L in the pond.
Low ammonia levels are common in the surface waters of most lakes because algae and
macrophytes quickly use any available ammonia for growth and reproduction. However, in
deeper lakes that stratify during the growing season, ammonia is produced as a by-product of
microbial decomposition and tends to accumulate below the thermocline. This was the case
during 2003.
During the 2003 growing season, hypolimnetic ammonia concentrations in Lake Carey were
much higher at the stratified lake than the uniformly mixed pond. The average hypolimnetic
ammonia concentrations were 0.61 mg/L at the lake and only 0.042 mg/L at the pond. The
maximum hypolimnetic ammonia concentration was 0.99 mg/L at the lake in late July. Under
anoxic conditions, bacteria at the lake bottom use nitrate instead of oxygen during their
metabolic activity. Ammonia is produced as a result of this nitrate reduction. It is therefore
common to find relatively high ammonia concentrations and low nitrate concentrations when
anoxic conditions exist at the lake bottom, as was the case during the summer of 2003 in Lake
Carey.
Nitrate and nitrite concentrations were measured together during the 2003 Lake Carey
monitoring program because nitrite is an unstable form of nitrogen that is quickly converted into
nitrate. Nitrate/nitrite was not monitored during 2004. The highest 2003 growing season
nitrate/nitrite concentrations in the epilimnion were observed during early May at the lake (0.33
mg/L). Surface nitrate/nitrite concentrations averaged 0.16 mg/L at the lake and 0.09 mg/L at the
pond during 2003.
The 2003 growing season hypolimnetic nitrate/nitrite were lowest during the period of peak
water column stratification and anoxic conditions at the lake. Nitrate/nitrite concentrations at the
lake were lower in the hypolimnion than in the epilimnion due to bacterial decomposition at the
lake bottom. Hypolimnetic nitrate/nitrite concentrations averaged 0.07 mg/L at the lake and 0.12
mg/L at the pond. The highest 2003 growing season nitrate/nitrite concentration in the
hypolimnion was observed during early June at the pond station (0.24 mg/L).
The total Kjeldahl nitrogen (TKN) concentrations measured in Lake Carey during 2003 were
used to calculate the organic nitrogen concentration in the lake and pond. Organic nitrogen
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
33
F. X. Browne, Inc.
concentrations were higher in the pond than in the lake. Epilimnetic organic nitrogen
concentrations in the lake during the growing season ranged from 0.04 mg/L to 0.83 mg/L.
Epilimnetic organic nitrogen concentrations in the pond ranged from 0.25 mg/L to 1.54 mg/L
during the growing season. The average epilimnetic organic nitrogen concentrations were 0.26
mg/L in the lake and 0.68 mg/L in the pond. In the hypolimnion, organic nitrogen concentrations
were lower than in the surface waters, but still the concentrations were higher in the pond than
the lake. The average hypolimnetic organic nitrogen concentrations were 0.16 mg/L in the lake
and 0.43 mg/L in the pond.
Total nitrogen is a measure of all forms of nitrogen in a lake, both inorganic and organic. The
surface total nitrogen concentrations in Lake Carey increased during the growing season,
becoming especially high in the pond in late August 2003, as shown in Figure 4.15. The average
epilimnetic total nitrogen concentrations in Lake Carey during 2003 were 0.44 mg/L in the lake
and 0.79 mg/L in the pond. This means that the majority of the nitrogen in the surface waters of
both the lake and pond at Lake Carey occurs in the organic form. This was also the case in the
bottom waters of the pond where the average hypolimnetic organic nitrogen concentration was
0.59 mg/L. However, in the lake, the average hypolimnetic organic nitrogen concentration was
1.46 mg/L. This is due to the fact that ammonia (an inorganic form of nitrogen) was being
released from the sediments during anoxic lake conditions.
In general, the ammonia, nitrate/nitrite, and organic nitrogen concentrations measured in Lake
Carey during 2003 were typical of concentrations found in productive lakes. The fact that
majority of the nitrogen existing in Lake Carey during 2003 occurred in the organic form
indicates that nitrogen inputs to the lake via runoff and failing septic systems were high.
Lake Carey 2003
Surface Total Nitrogen Concentrations
1.8
Lake
Pond
1.6
Total Nitrogen (mg/L)
1.4
1.2
1
0.8
0.6
0.4
0.2
0
May-03
Jun-03
Jul-03
Aug-03
Figure 4.15 Surface total nitrogen concentrations at Lake Carey during 2003
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
34
F. X. Browne, Inc.
Limiting Nutrient
Algal growth depends on a variety of nutrients including macronutrients such as phosphorus,
nitrogen, and carbon, and trace nutrients such as iron, manganese, and other minerals. According
to Liebig's Law of the Minimum, biological growth is limited by the substance that is present in
the minimum quantity with respect to the needs of the organism. Nitrogen and phosphorus are
usually the nutrients limiting algal growth in most natural waters.
Depending on the species, algae require approximately 15 to 26 atoms of nitrogen for every atom
of phosphorus. This ratio converts to 7 to 12 mg of nitrogen per 1 mg of phosphorus on a mass
basis. A ratio of total nitrogen to total phosphorus of 15:1 is generally regarded as the dividing
point between nitrogen and phosphorus limitation (U.S. EPA, 1980). Identification of the
limiting nutrient becomes more certain as the total nitrogen to total phosphorus ratio moves
farther away from the dividing point, with ratios of 10:1 or less providing a strong indication of
nitrogen limitation and ratios of 20:1 or more strongly indicating phosphorus limitation.
Inorganic nutrient concentrations may provide a better indication of the limiting nutrient because
the inorganic nutrients are the forms directly available for algal growth. Ratios of total inorganic
nitrogen (TIN = ammonia, nitrate, and nitrite) to dissolved reactive phosphorus (DRP) greater
than 12 are indicative of phosphorus limitation, ratios of TIN:DRP less than 8 are indicative of
nitrogen limitation, and TIN:DRP ratios between 8 and 12 indicate either nutrient can be limiting
(Weiss, 1976).
At Lake Carey, the average total nitrogen to total phosphorus ratio (TN:TP) at the lake station
was 6:1 and the total inorganic nitrogen to dissolved reactive phosphorus ratio (TIN:DRP) was
9:1 as shown in Table 4.1. At the pond station, the average total nitrogen to total phosphorus
ratio (TN:TP) was 6:1 and the total inorganic nitrogen to dissolved reactive phosphorus ratio
(TIN:DRP) was 8:1 as shown in Table 4.2.
Because the usable forms of both phosphorus and nitrogen were occasionally below detectable
levels in the photic zone of Lake Carey during the growing season and because the phosphorus
concentrations were so high, it is difficult to generalize about which nutrient limited algal
growth. It is likely that the limiting nutrient alternated between nitrogen and phosphorus during
the summer, depending upon the nutritional requirements of the dominant algal species at any
particular time. However, the dominance of nitrogen (atmospheric) fixing, blue-green
phytoplankton during the summer and fall and the above nitrogen-phosphorus ratios suggests
that nitrogen became depleted during the summer, and therefore, became limiting during this
time.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
35
F. X. Browne, Inc.
Date
5/13/03
6/8/03
7/26/03
8/23/03
Average
Date
5/13/03
6/8/03
7/26/03
8/23/03
Average
Table 4.1
Lake Carey Nitrogen- Phosphorus Ratios
Lake Station
Total Inorganic Nitrogen:
Total Nitrogen: Total Phosphorus
Dissolved Reactive Phosphorus
TN:TP
TIN:DRP Ratio
Result
Result
Ratio
21.7
Phosphorus
5.8
Nitrogen
11.8
Either
4.0
Nitrogen
0.8
Nitrogen
0.8
Nitrogen
2.9
Nitrogen
13.0
Phosphorus
9.3
Nitrogen
5.9
Nitrogen
Table 4.2
Lake Carey Nitrogen- Phosphorus Ratios
Pond Station
Total Inorganic Nitrogen:
Total Nitrogen: Total Phosphorus
Dissolved Reactive Phosphorus
TN:TP
TIN:DRP Ratio
Result
Result
Ratio
11.8
Either
7.6
Nitrogen
15.0
Either
8.9
Either
1.7
Nitrogen
1.1
Nitrogen
4.4
Nitrogen
4.7
Nitrogen
8.2
Nitrogen
5.6
Nitrogen
TIN:DRP (mg/L N:mg/L P)
less than or equal to 10
10-20
greater than or equal to 20
Nutrient Limiting Phytoplankton Yield
Nitrogen
Nitrogen and/or Phosphorus
Phosphorus
TN:TP (mg/L N:mg/L P)
less than or equal to 8
8-12
greater than or equal to 12
Nutrient Limiting Phytoplankton Yield
Nitrogen
Nitrogen and/or Phosphorus
Phosphorus
4.1.3
Lake and Pond Biological Interactions
Phytoplankton
Phytoplankton are microscopic algae that have little or no resistance to currents and live freefloating, suspended in open water. Algal cells may be unicellular, colonial, or filamentous. As
photosynthetic organisms (primary producers), phytoplankton form the basis of the aquatic foodweb and are grazed upon by zooplankton and herbivorous fish.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
36
F. X. Browne, Inc.
A healthy lake should support a diverse assemblage of phytoplankton represented by a variety of
algal species. Excessive phytoplanktonic growth, which typically consists of a few dominant
species, is undesirable. Excessive growth can result in severe
oxygen depletion in the water at night, when the algae are
respiring (using up oxygen) and not photosynthesizing
(producing oxygen). Oxygen depletion can also occur after an
algal bloom when bacteria grow and multiply using dead algal
cells as a food source. Excessive growths of some species of
algae, particularly members of the blue-green group, may cause
taste and odor problems, release toxic substances to the water,
or give the water an unattractive green soupy or scummy
appearance. An incidence of a toxic reaction to an Anabaena
algae bloom was recorded in 1979 at Lake Carey (Ulanoski, et.
al., 1981). Algae toxins can be a serious public health concern.
Planktonic productivity is commonly expressed by enumeration and biomass. Enumeration of
phytoplankton is expressed as cells per milliliter (cells/mL). Biomass is expressed on a mass per
volume basis as micrograms per liter (μg/L). Of the two, biomass provides a better estimate of
the actual standing crop of phytoplankton in lakes.
Lake Carey phytoplankton samples were collected once per month at both the lake and the pond
between May and August 2003. The phytoplankton samples were composite samples collected
from the photic zone as measured on each sampling date. Organisms were identified to the genus
level and enumerated. Biomass for each genus was determined from size and density
calculations. All phytoplankton data are presented in Appendix D.
Total and blue-green phytoplankton densities measured at the lake during 2003 are represented
graphically in Figure 4.16. Figure 4.17 shows the total and blue-green phytoplankton biomasses
at the lake during 2003. The pond total and blue-green phytoplankton densities are shown in
Figure 4.18 and the pond biomasses are shown in Figure 4.19.
Phytoplankton counts were high at both the lake and pond during the 2003 growing season.
During the study period, five taxa (groups) of phytoplankton were identified at the lake station in
Lake Carey including Bacillariophyta (diatoms), Chlorophyta (green algae), Chrysophyta
(golden brown algae), Cryptophyta (cryptomonads), and Cyanophyta (blue-green algae). The
pond contained seven taxa of phytoplankton: Bacillariophyta (diatoms), Chlorophyta (green
algae), Chrysophyta (golden brown algae), Cryptophyta (cryptomonads), Cyanophyta (bluegreen algae), Euglenophyta (Euglena), and Pyrrhophyta (dinoflagellates). Blue-green
phytoplankton species dominated the phytoplankton population in terms of both density and
biomass from June through August at both the lake and pond. During May 2003, diatoms
(Bacillariophyta) dominated the density and biomass at the lake. At the pond in May, goldenbrown algae (chrysophytes) dominated the phytoplankton density and diatoms dominated the
biomass. Aphanizomenon was the most dominant blue-green species at the lake, with Anabaena
also present in high numbers. Aphanizomenon was also dominant at the pond, with several other
blue-green species also present.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
37
F. X. Browne, Inc.
Lake Carey 2003
Phytoplankton Density
Lake Station
90000
Total Phytoplankton
Blue-Green Phytoplankton
Phytoplankton Density (cells/mL)
80000
70000
60000
50000
40000
30000
20000
10000
0
May-03
Jun-03
Jul-03
Aug-03
Figure 4.16 Phytoplankton density at Lake Carey lake during 2003
Lake Carey 2003
Phytoplankton Biomass
Lake Station
12000
Total Phytoplankton
Blue-Green Phytoplankton
Phytoplankton Biomass (µg/L)
10000
8000
6000
4000
2000
0
May-03
Jun-03
Jul-03
Aug-03
Figure 4.17 Phytoplankton biomass at Lake Carey lake during 2003
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
38
F. X. Browne, Inc.
Lake Carey 2003
Phytoplankton Density
Pond Station
120000
Total Phytoplankton
Blue-Green Phytoplankton
Phytoplankton Density (cells/mL)
100000
80000
60000
40000
20000
0
May-03
Jun-03
Jul-03
Aug-03
Figure 4.18 Phytoplankton density at Lake Carey pond during 2003
Lake Carey 2003
Phytoplankton Biomass
Pond Station
14000
Total Phytoplankton
Blue-Green Phytoplankton
Phytoplankton Biomass (µg/L)
12000
10000
8000
6000
4000
2000
0
May-03
Jun-03
Jul-03
Aug-03
Figure 4.19 Phytoplankton biomass at Lake Carey pond during 2003
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
39
F. X. Browne, Inc.
The 2003 seasonal average total phytoplankton density was 38,742 cells/mL at the lake and
53,382 cells/mL at the pond. The seasonal average total biomass in Lake Carey during 2003 was
5,595 µg/L at the lake and 7,917 µg/L at the pond. The peak blue-green algae concentration was
82,980 cells/mL at the lake and 97,900 cells/mL at the pond, both during late July 2003.
The high phytoplankton densities in 2003 were most likely exacerbated by the large rain events
during the late spring contributing high nutrient loads to the lake, followed by hot, dry conditions
during the middle of the summer. These conditions are especially conducive to algae blooms.
Algal Assays
Algae growth depends on a variety of nutrients, including macronutrients such as phosphorus,
nitrogen and carbon, and trace nutrients such as iron and manganese. According to the law of the
minimum, biological growth is limited by the substance that is present in the minimum quantity
with respect to the needs of the organism. Nitrogen and phosphorus are usually the nutrients
limiting growth in most natural waters.
Because of the close relationship between nutrient concentrations and algae growth in lakes, lake
managers try to control nutrient loadings in order to control algae growth in the lake. In order to
do this effectively, the nutrient which limits the growth of the algae must be identified and
controlled. The biostimulation procedure (EPA, 1978, the Selenastrum capricornutum Printz
Algal Assay Bottle Test) uses algae grown under very controlled conditions to determine which
nutrient limits algae growth. Instead of judging the water quality of a lake based on the nutrient
concentrations measured in the water alone, the biostimulation study evaluates the nutrient
effects more directly, by determining which nutrient actually makes algae grow more when it is
added to lake water.
Algal assays were performed at both the lake and pond at Lake Carey during 2003 and 2004 by
adding Selenastrum capricornutum to the test water and determining algal growth at appropriate
intervals. The results were somewhat indeterminate, since the algae grew best when both
phosphorus and nitrogen were added to the lake water, as shown in Figure 4.20 through Figure
4.23. This corresponds to the limiting nutrient calculations based on water quality testing,
indicating that either phosphorus or nitrogen could be limiting in the lake and pond, depending
on the nutritional needs of the phytoplankton population at a given time. Because the phosphorus
concentrations in Lake Care are so high, nitrogen was the limiting nutrient by default during
much of the growing season.
The results of both the algal assay and the limiting nutrient calculations indicate that it is
important to control both phosphorus and nitrogen inputs to Lake Carey. Phosphorus inputs are
easier to control via lake and watershed BMPs. Nitrogen is more difficult to manage in a lake or
pond system since it occurs in the dissolved form rather than being associated with sediment
particles like phosphorus. Also, certain species of blue-green algae can fix nitrogen from the
atmosphere regardless of how little nitrogen is entering the lake via stormwater runoff.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
40
F. X. Browne, Inc.
Lake Carey
Biostimulation Study 2003
Selenastrum - Lake
250
Control
Phosphorus
Nitrogen
Phosphorus + Nitrogen
Chlorophyll a Fluorescence
200
150
100
50
0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
Days in Experiment
Figure 4.20 Algal assay results for Lake Carey lake during 2003
Lake Carey
Biostimulation Study 2003
Selenastrum - Pond
250
Control
Phosphorus
Nitrogen
Phosphorus + Nitrogen
Chlorophyll a Fluorescence
200
150
100
50
0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
Days in Experiment
Figure 4.21 Algal assay results for Lake Carey pond during 2003
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
41
F. X. Browne, Inc.
Lake Carey
Biostimulation Study 2004
Selenastrum - Lake
250
Control
Phosphorus
Nitrogen
Phosphorus + Nitrogen
Chlorophyll a Fluorescence
200
150
100
50
0
0
1
2
3
4
5
6
7
8
9
10
Days in Experiment
11
12
13
14
15
16
Figure 4.22 Algal assay results for Lake Carey lake during 2004
Lake Carey
Biostimulation Study 2004
Selenastrum - Pond
250
Control
Phosphorus
Nitrogen
Phosphorus + Nitrogen
Chlorophyll a Fluorescence
200
150
100
50
0
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Days in Experiment
Figure 4.23 Algal assay results for Lake Carey pond during 2004
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
42
F. X. Browne, Inc.
Zooplankton
Zooplankton are small aquatic invertebrates that graze on phytoplankton and are in turn preyed
upon by larger invertebrates and planktivorous fish. During 2003, the zooplankton population of
Lake Carey was sampled monthly at each station from May through August. Density and
biomass of each zooplankton genera were measured in the same manner as they were for the
phytoplankton.
The zooplankton population at Lake Carey was fairly low at both the lake and pond. Rotifers,
copepods, and cladocerans were present at both stations during 2003. Different species
dominated the zooplankton density during each month and varied per station. The total
zooplankton densities ranged from 6.6 individuals/per liter (ind/L) during June to 206 ind/L
during July. In general, cladocerans dominated the zooplankton biomass at both stations during
2003. Cladocerans were dominant during June, July, and September. The total zooplankton
biomasses ranged from 11 µg/L during June to 229 µg/L during July. Typically, zooplankton
populations are low when blue-green algae populations are high, since blue-green algae are not
palatable to most zooplankton.
The average zooplankton mean body length was 0.42 mm during 2003. Average zooplankton
mean body lengths less than 0.5 mm usually indicate an unbalanced fishery, with an abundance
of panfish. All zooplankton data are presented in Appendix E.
Chlorophyll a
Water samples containing phytoplankton can be processed to extract chlorophyll a from algal
cells for analysis. Chlorophyll a is a green pigment used by plants to convert sunlight to chemical
energy during photosynthesis. Chlorophyll a constitutes about 1 to 2 percent of the dry weight of
planktonic algae, so the amount of chlorophyll a in a water sample is an indicator of
phytoplankton biomass. Pheophytin a is a degradation product of chlorophyll a. Determining the
pheophytin a concentration in a water sample enables a more accurate measurement of the
chlorophyll a concentration in the sample. Both the chlorophyll a and pheophytin a data for 2003
and 2004 at Lake Carey are presented in Appendix C.
The Lake Carey chlorophyll a concentrations were higher at the pond than at the lake during both
2003 and 2004. During 2003, the chlorophyll a concentrations increased at both the lake and the
pond throughout the growing season and peaked during August as shown in Figure 4.24. During
2004, the highest chlorophyll a concentrations occurred during late June at both the lake and
pond, and decreased during July. This decrease may have been due to large storms with heavy
rainfall that occurred during the mid to late summer in 2004 that most likely flushed the algae
populations out of the lake and pond. The 2004 chlorophyll a concentrations at Lake Carey are
shown graphically in Figure 4.25.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
43
F. X. Browne, Inc.
Lake Carey 2003
Chlorophyll a Concentrations
50.0
Lake
Pond
45.0
40.0
Chlorophyll a (ug/L)
35.0
30.0
25.0
20.0
15.0
10.0
5.0
0.0
May-03
Jun-03
Jul-03
Aug-03
Figure 4.24 Chlorophyll a concentrations in Lake Carey during 2003
Lake Carey 2004
Chlorophyll a Concentrations
50.0
Lake
Pond
45.0
40.0
Chlorophyll a (ug/L)
35.0
30.0
25.0
20.0
15.0
10.0
5.0
0.0
May-04
Jun-04
Jul-04
Aug-04
Figure 4.25 Chlorophyll a concentrations in Lake Carey during 2004
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
44
F. X. Browne, Inc.
The chlorophyll a concentrations at the lake during 2003 ranged from 2.2 µg/L to 37.0 µg/L with
an average concentration of 16.3 µg/L. Chlorophyll a concentrations were higher at the pond
during 2003, ranging from 24.0 µg/L to 43.0 µg/L with an average of 30.7 µg/L. The 2004
ranges and averages were similar to the 2003 ranges and averages at both the lake and pond.
During 2004, the chlorophyll a concentration at the lake ranged from 5.1 µg/L to 29.0 µg/L with
an average of 16.0 µg/L. At the pond, the chlorophyll a concentration ranged from 6.0 µg/L to
43.0 µg/L with an average of 29.0 µg/L during 2004
The U.S. Environmental Protection Agency (US EPA) has established classification criteria for
chlorophyll a concentrations in lakes and ponds. According to this classification, lakes and ponds
that have chlorophyll a concentrations of less than 4 µg/L are indicative of oligotrophic
conditions, lakes and ponds with chlorophyll a concentrations between 4 and 10 µg/L are
indicative of mesotrophic conditions, and lakes and ponds with chlorophyll a concentrations
greater than 10 µg/L are considered to be eutrophic. Therefore, based on US EPA criteria for
chlorophyll a, Lake Carey would be classified as eutrophic.
The pheophytin a concentrations at both the lake and pond stations at Lake Carey were near
below detection limits during the study period. This indicates that very little of the chlorophyll a
concentration can be attributed to pheophytin a.
Macrophytes
Aquatic vegetation ranges from tiny microscopic algae to large vascular aquatic plants which are
called macrophytes. Macrophytes can be found rooted to the lake bottom or floating on the lake's
surface. Based on growth and habitat characteristics, macrophytes generally can be classified in
one of three categories: submerged aquatic vegetation, floating aquatic vegetation, and emergent
aquatic vegetation. Submerged aquatic plants live and grow completely underwater or just up to
the surface of the water. A few submerged species protrude just above the water surface when in
flower. Floating aquatic plants are those plants whose leaves float on the surface of the water.
These plants may or may not be anchored to the bottom of the lake via stems or roots. Emergent
aquatic plants have their upper stems and leaves protruding above the surface of the water. These
plants are always attached directly to the lake bottom via root systems.
A certain amount of macrophytes are beneficial to a lake or pond system, providing habitat for
fish and helping to oxygenate the water. However, high nutrient and sediment levels in a lake or
pond can cause macrophytes to grow to excess, choking waterways, altering the ecosystem, and
inhibiting recreation. In general, the current density of macrophytes in Lake Carey is not
considered excessive. Macrophytes occur along the shoreline, and in the shallower bays and
more stagnant areas of the lake and pond. According to the report “Trophic Classification and
Characteristics of Twenty-Six Publicly Owned Pennsylvania Lakes” (Ulanoski, et. al., 1981),
aquatic macrophytes have historically been moderately plentiful in Lake Carey. It is likely that
the excessive phytoplankton populations in the lake and pond inhibit sunlight penetration into the
water, thereby limiting macrophyte growth.
It is recommended that a formal baseline macrophyte survey be conducted by a professional
ecologist in order to document the macrophyte species present and determine whether any of
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
45
F. X. Browne, Inc.
those macrophytes are non-native, invasive species. If any invasive species are found, steps
should be taken to eradicate them immediately. Members of the Lake Carey Cottages
Association should receive training in identification of the types of macrophytes found in Lake
Carey as well as potential invasive species so that they can conduct annual macrophyte surveys
at the lake and pond. This will become especially important once phytoplankton levels are
reduced since an increase in sunlight penetration in the lake and pond water will likely lead to an
increase in macrophyte growth. If in the future the macrophyte populations become excessive,
the Lake Carey Cottages Association should hire a macrophyte management company to address
the problem.
Bacteria
Members of two bacteria groups, coliforms and fecal streptococci, are used as indicators of
possible sewage contamination because they are commonly found in human and animal feces.
Although they are generally not harmful themselves, they indicate the possible presence of
pathogenic (disease-causing) bacteria, viruses, and protozoans that also live in human and animal
digestive systems. Therefore, their presence in lakes and ponds suggests that pathogenic
microorganisms might also be present and that swimming and eating shellfish might be a health
risk. Sources of fecal contamination to surface waters include wastewater treatment plants, onsite septic systems, domestic and wild animal manure, and stormwater runoff.
Fecal coliform and fecal streptococci were monitored in the pond and the lake at Lake Carey
during 2003. During all the sampling periods, bacteria levels were either very low or below
detection limits at both stations. The highest measured bacteria concentration was 20 cells/100
mL, which occurred at the lake during July 2003 and at the pond during August 2003. The
bacteria concentrations in Lake Carey do not exceed PA Code Chapter 93 regulations for
recreational water contact or potable water supply. However, lake and pond samples were not
collected immediately after storm events, and based on the results from the stream monitoring
program, it is likely that bacteria concentrations were temporarily elevated following storms.
4.1.4
Lake and Pond Trophic State Index
Carlson's Trophic State Index values (TSI values) (Carlson, 1977) are used to describe the
trophic state of a lake in terms of the relationships among phytoplankton biomass, water
transparency, nutrient concentrations, and chlorophyll a concentrations. TSI values are calculated
using Secchi disk transparency readings, chlorophyll a concentrations, and total phosphorus
concentrations. Carlson TSI values are based on a scale of 0 to 100. Lakes with TSI values of
less than 40 are classified as oligotrophic, while lakes with TSI values of 50 or greater are
classified as eutrophic, according to the US EPA.
All three trophic state indices were calculated using 2003 and 2004 growing season data (May
through August) collected at both the lake and pond stations at Lake Carey. The results are
shown graphic form in Figure 4.26 and Figure 4.27. Based on the 2003 and 2004 TSI
calculations and the US EPA criteria, the Lake Carey lake is considered to be eutrophic and the
pond is considered to be eutrophic to hyper-eutrophic.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
46
F. X. Browne, Inc.
Lake Carey 2003
Trophic State Indices
100
Lake
Pond
90
Hyper-eutrophic
80
Trophic State Index Value
80
70
66
60
64
Eutrophic
61
58
50
49
40
30
20
10
0
Total Phosphorus
Chlorophyll a
Secchi Depth
Figure 4.26 Trophic State Indices at Lake Carey during 2003
Lake Carey 2004
Trophic State Indices
100
Lake
Pond
90
Hyper-eutrophic
Trophic State Index Value
80
76
70
60
59
64
Eutrophic
64
58
55
50
40
30
20
10
0
Total Phosphorus
Chlorophyll a
Secchi Depth
Figure 4.27 Trophic State Indices at Lake Carey during 2004
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
47
F. X. Browne, Inc.
4.1.5
Bathymetric Surveys and Sediment Testing
As part of a lake study, samples of the accumulated lake bottom sediments are often collected
and analyzed for nutrients and other parameters that may affect biological reactions within the
lake. Sediment test results are useful to assess the potential impacts of the internal release of
nutrients into the water column by in-lake sediments. In general, sediments are comprised of
organic matter (decaying macrophytes and algae), inorganic mineral soils, and water. Inorganic
materials (eroded soils) are typically deposited into a lake by its tributary streams which
transport these materials from points of erosion within the lake's watershed. Sediment testing
data is provided in Appendix F.
Both iron and manganese tend to be released along with phosphorus from lake sediments under
anoxic conditions. Under well-oxygenated conditions, iron can actually bind phosphorus, thereby
preventing its release into the water column. One set of samples were collected from five sites in
the lake and pond at Lake Carey during August of 2003 and analyzed for total phosphorus, iron
and manganese.
Iron and manganese were present in the lake sediments at all five locations. Iron concentrations
were similar in both the lake and the pond sediments. Manganese concentrations were higher in
the pond sediments than in the lake sediments. This could have been due to naturally-occurring
mineral deposits. Total phosphorus concentrations were higher in the lake sediments than the
pond sediments. The highest total phosphorus concentrations were in the sediments adjacent to
the area of most concentrated development around the lake. These results show that
concentrations of total phosphorus, iron, and manganese are present in lake and pond sediments
at high enough levels that would allow the release of these compounds into the lake water under
anoxic conditions.
A bathymetric survey was conducted at Lake Carey by volunteers using a fathometer to
determine the water depth and the thickness of accumulated sediments. A bathymetric map of the
lake resulting from this survey is provided in Figure 4.28 and a sediment thickness map of the
lake is provided in Figure 4.29. The areas of highest sediment accumulation were around the lake
inlets, especially the inlets on the southeastern shore of the lake. The Lake Carey lake contains
approximately 1.2 million cubic yards of sediment with an average sediment thickness of 4.1
feet. A bathymetric map of the pond is provided in Figure 4.30 and a sediment thickness map of
the pond is provided in Figure 4.31.The pond contains approximately 291,200 cubic yards of
sediment with an average sediment thickness of 2.6 feet.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
48
F. X. Browne, Inc.
Figure 4.28 Bathymetric Map of Lake Carey Lake
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
49
F. X. Browne, Inc.
Figure 4.29 Sediment Thickness Map of Lake Carey Lake
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
50
F. X. Browne, Inc.
Figure 4.30 Bathymetric Map of Lake Carey Pond
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
51
F. X. Browne, Inc.
Figure 4.31 Sediment Thickness Map of Lake Carey Pond
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
52
F. X. Browne, Inc.
4.2
Stream Monitoring
Stream monitoring was performed at a number of streams in the Lake Carey watershed during
2003. Additional stream monitoring was conducted by volunteers at Meade Brook and the
Stevens Lake tributary during 2004. All stream water quality data is provided in Appendix G.
Baseflow (dry weather) samples were collected on August 9, 2004, and stormflow (wet weather)
samples were collected on August 10, 2004. The results of the wet weather and dry weather
monitoring are provided in Table 4.3. The results show that the total phosphorus, total suspended
solids, and bacteria concentrations increase dramatically under stormflow conditions. However
the majority of the inorganic and organic nitrogen enters Lake Carey under baseflow conditions.
Parameter
Table 4.3
Lake Carey 2004 Stream Monitoring
Wet
Meade Brook
Stevens Lake Tributary
Weather
Baseflow
Stormflow
Baseflow
Stormflow
Deposition
0.40
0.30
0.24
0.15
0.04
< 0.1
< 0.1
< 0.1
< 0.1
Nitrate Nitrogen
Ammonia Nitrogen
Total Suspended
<1
1.2
Solids
Total Phosphorus
0.027
0.056
Total Kjeldahl
0.41
0.34
Nitrogen
Alkalinity
62
Fecal Coliform
22
(#/100mL)
Fecal Streptococcus
34
(#/100 mL)
Note: All values in mg/L unless otherwise stated
4.3
9.2
6.8
14
0.102
0.052
0.084
0.37
0.71
0.56
52
36
30
1600
560
340
4600
109
1260
Alum Studies
Jar testing was conducted on stream water entering Lake Carey from Meade Brook to evaluate
alum treatment as a restoration alternative for Lake Carey. Test water was collected from Meade
Brook on 8/9/04 (dry event) and 8/10/04 (wet event) and analyzed for pH, alkalinity, total
phosphorus, and dissolved reactive phosphorus. Each jar test consisted of six one-liter beakers
filled with test water spiked with a predetermined alum concentration. The beakers were
immediately stirred at 100 revolutions per minute for 90 seconds followed by 30 revolutions per
minute for 10 minutes. Once the mixing stopped, observations were made every five minutes for
an additional 60 minutes noting floc formation and settling rates. Samples of the supernatant of
each jar test were analyzed for pH, alkalinity, and total phosphorus. Dissolved reactive
phosphorus was analyzed on the particular jar test judged to have the optimum settling rate and
phosphorus removal. The results of the jar testing are provided in Appendix H.
Based on the results of the jar tests, the alum dose that would be optimum for removing
phosphorus from the water in Meade Brook would be 64 mg/L.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
53
F. X. Browne, Inc.
4.4
Groundwater Well Monitoring
Groundwater quality in the Lake Carey watershed was monitored by analyzing key parameters in
residential water wells near Lake Carey. Voluntary surveys were conducted on several different
dates. Questionnaires and sample bottles were provided to interested homeowners within
approximately ¼ mile of Lake Carey. Samples were collected by the homeowners and analyzed
at the Wilkes University laboratory. A summary of the survey results is provided in Table 4.4
and a complete list of well water quality data is provided in Appendix I. Of particular concern is
the fact that out of the 50 wells tested, 82 percent tested positive for total coliform bacteria and
38 percent tested positive for fecal coliform bacteria. This indicates that wastewater
contamination is most likely very prevalent in and around Lake Carey. Another significant
concern is that 40 percent of the wells tested exceeded drinking water standards for lead at the
tap. Homeowners in the Lake Carey watershed were made aware of these issues. Homeowners
should be informed about drinking water protection measures and the importance of frequent
drinking water testing.
Table 4.4
Groundwater Well Monitoring Results in Lake Carey Watershed
Number of
Recommended
Parameter
Measured Range
Groundwater
Range
Standard Exceedances
pH
5.8 to 8.4
6.5 - 8.5
14
(pH Units)
1 may exceed TDS
Conductivity
32 to 700
no standard
Level
(uS/cm)
Alkalinity
24 to 198
no standard
0
(mg CaCO3)
Hardness *
5 to 750
< 100 to 160
32
(mg CaCO3)
4 to 230
< 250
0
Chloride (mg/L)
< 5 to 37
< 250
0
Sulfate (mg/L)
< 0.05 to 3.7
< 10
0
Nitrate (mg N/L)
Orthophosphate
(ppb)
< 0.01 to 11.7
< 1.0
7
Copper (ppm)
< 0.01 to 2.07
< 0.3
3
Iron (ppm)
< 0.005 to 1.46
< 0.05
10
Manganese (ppm)
< 0.01 to 5.86
<5
1
Zinc (ppm)
1.91 to 45.3
no standard
Sodium* (ppm)
< 0.0005 to 0.74
< 0.015 (at tap)
20
Lead (ppm)
< 0.0005 to 0.74
< 0.005 (in system)
30
Total Coliform
< 1 to TNTC
0
41
(colonies/100mL)
Fecal Coliform
absent
19
(Present/Absent)
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
54
F. X. Browne, Inc.
4.5
Water quality Summary and Conclusions
Based upon the results of the monitoring program, including total phosphorus concentration,
chlorophyll a concentration, Secchi disk transparency, and Carlson's Trophic State Index, as well
as U.S. EPA trophic state criteria, Lake Carey is classified as eutrophic to hyper-eutrophic.
Severe dissolved oxygen depletion in the hypolimnion at the lake station leads to release of
phosphorus and ammonia from the sediments. The pond station remained well mixed.
Because the phosphorus concentrations in Lake Carey are excessively high, the limiting nutrient
in both the lake and pond appears to be nitrogen. Phytoplankton densities and biomasses at both
stations are extremely high, and undesirable blue-green algae species dominate the
phytoplankton population. Stream water quality monitoring results show that excessive amounts
of phosphorus, sediment, and bacteria are entering Lake Carey during storm events. Both in-lake
and watershed management practices would be beneficial to the water quality at Lake Carey.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
55
F. X. Browne, Inc.
5.0
Watershed Evaluations
Watershed investigations for nonpoint source pollution problem areas in the Lake Carey
Watershed were performed by volunteers from the Lake Carey Cottages Association. Problem
areas were identified on a map, GPS coordinates were measured at each site, a photograph of the
problem area was taken, a description of the problem was prepared, and an assessment as to the
severity of the problem was assigned to each area. The problem areas are shown on Figure 5.1
and presented in Table 5.1.
Agricultural problem areas were not identified as part of this study. However, the estimated
phosphorus loading to Lake Carey is relatively high from agricultural land uses. The TMDL
report for Lake Carey completed by the Susquehanna River Basin Commission in March 2001
indicated that many BMPs have been installed on farms in the Lake Carey Watershed, and the
agricultural phosphorus load from agricultural land in the Lake Carey has been significantly
reduced. The report also indicated, however, that since the effectiveness of these BMPs has not
been assessed, agricultural runoff must still be addressed to reduce the pollutant loading in the
Lake Carey Watershed.
Other typical problems that were identified in
the Lake Carey Watershed during the
watershed investigations include streambank
erosion, shoreline erosion, roadside erosion,
erosion from driveways, construction site
erosion, and failing on-site wastewater
systems.
5.1
Streambank and Shoreline
Erosion
Several streambank and shoreline erosion
problem areas were identified during the
watershed investigations. These problem areas
are a direct source of sediment and nutrients to
Lake Carey and should be stabilized using a
vegetative and/or structural methods.
5.2
Roadside Erosion along a paved road in
the Lake Carey Watershed
Road and Driveway Erosion
Roadside erosion along paved roads and dirt
and gravel roads in the Lake Carey Watershed
was observed during the watershed surveys.
Many of the paved roads in the watershed lack
adequately sized drainages swales. As a result,
excessive volumes of stormwater runoff create
ditches along the roads that travel to the
nearest stream via unstabilized channels.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
Streambank erosion in the Lake Carey
Watershed
PA1590-01-001
56
F. X. Browne, Inc.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
57
F. X. Browne, Inc.
Table 5.1
Nonpoint Source Pollution Problem Areas in Lake Carey Watershed
(See Figure 5.1 for actual locations)
Location
No.
Description
Impact
1
2
Mead Brook, bank erosion due to filled stream bed and cutting by current
Unfiltered Runoff from farm land, under abandoned rail bed to stream and then lake
Moderate
Moderate
3
Bank erosion just prior to road, homeowner trying to stabilize.
Severe
4
Headworks of stream to A3, farm runoff and grass fields, many roads through forest vs. trees,
can see where significant runoff has occurred in the past.
Severe
5
Deep cut into ground, flow originates from farm/woods
Moderate
6
Moderate
9
10
11
12
13
Bank erosion, same area as location 5
Road washout on Flow Pond - major siltation source during almost any rainfall due to slope
of road
Location of failed septic, almost never dry flow
Road washout on Flow Pond - major siltation source during almost any rainfall due to slope
of road
Driveway washout.
Parking Lot, unpaved with some gravel
Driveway washout.
Demellier Road erosion, ruts from washouts
14
15
16
17
18
Lake patio erosion, small ruts
Storm drain erosion
Bank erosion, reforest.
Driveway washout.
Shoreline erosion
Minimal
Moderate
Moderate
Moderate
Minimal
19
20
Bank/driveway erosion
Potential failed septic system, dark green algae in ponded water by home
Moderate
Moderate
21
22
Culvert at Sherwoods cottage, bank erosion, soap suds, color
Driveway washout.
Moderate
Minimal
23
24
25
26
27
28
29
Driveway washout.
Holbrook Rd. washout
Culvert at Givler's Cottage
Culvert, some color and bank erosion
Tree harvesting drop, major erosion/damage
Stream with severe bank erosion
Mead Brook, good bank coverage, not much silt after heavy rain.
Minimal
Moderate
Moderate
Moderate
Severe
Severe
Moderate
30
31
Moderate
Severe
32
33
34
35
36
Bank and stream erosion from farm fields and deforesting
Construction site, exposed dirt/mud.
Culvert, farm runoff, bank erosion, source of considerable siltation during heavy rains this
year. Have homeowner video.
Culvert, bank erosion.
bank erosion along road
Brook from Steven's Lake, flows through tornado damaged area, some silt
Culvert, Indian Springs, large flow from trailer smells bad, high bacteria last testing
37
Frank's Marina boat launch - some erosion
Minimal
7
8
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
Severe
Severe
Severe
Minimal
Moderate
Moderate
Moderate
Moderate
Moderate
Severe
Severe
Severe
PA1590-01-001
58
F. X. Browne, Inc.
Adequately
designed,
stabilized
roadsideswales should be installed along all
paved roads in the watershed to eliminate
this problem. Water should be directed to
filter strips or other treatment devices prior
to flowing into streams.
Dirt and gravel roads are also a problem in
the Lake Carey watershed. Improperly
graded roads with no real drainage systems
allow muddy water to runoff these roads and
in many cases directly into streams. In some
cases, the runoff from these roads is directed
into forested areas that help to filter the
pollutants from the stormwater runoff.
Gravel driveways and parking lots are also a
problem, and many eroded driveways were
identified during the watershed survey.
5.3
Gravel parking lot runoff directly to Lake
Carey
Construction and Other Erosion Sites
Erosion from construction sites and miscellaneous erosion areas were also identified during the
watershed surveys. Development and implementation of erosion control ordinances are a good
way to address construction related erosion problems. Other erosion areas, such as erosion of
banks and miscellaneous erosion areas need to be stabilized with vegetative and structural
methods.
5.4
Failing Septic Systems
Evidence of failing septic systems was observed at one location during the watershed surveys. It
is probably that many of the septic systems surrounding that lake are failing based on the age of
the systems and the poor soil conditions throughout the watershed.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
59
F. X. Browne, Inc.
6.0
Pollutant Loadings to Lake Carey
Pollutants can enter a lake from both point and nonpoint sources. Point sources are defined as all
wastewater effluent discharges within a watershed. Point source pollutants may be discharged
into streams and then transported to lakes or directly discharged into lakes. All other pollutant
sources within a watershed are classified as nonpoint sources. Nonpoint sources can contribute
pollutants to a water body during base flow (low flow) or storm flow (high flow) conditions
through inflow from tributary streams, direct runoff, direct precipitation on the lake surface, or
through internal loading via lake sediments and groundwater inputs. Both natural events, such as
precipitation and runoff, and human activities, including agriculture, silviculture, septic systems,
and construction, can contribute pollutants to the lake system. Nonpoint sources can be difficult
to quantify but are important because they often constitute the major source of pollutants to
waterbodies. Storm flow conditions typically contribute large quantities of water with relatively
high pollutant concentrations over relatively short durations throughout a given study period, and
are therefore a very significant portion of any pollutant budget. Base flow, however, typically
contributes lower quantities of water with relatively low pollutant concentrations over relatively
long durations throughout a given study period, which also results in significant nonpoint source
pollutant loadings.
Development of an accurate hydrologic budget is the first step in determining pollutant loadings
to a lake. In this study, an annual hydrologic budget was estimated for the Lake Carey using
existing stream gauging stations, information from similar watersheds, and published values of
rainfall during 2003. Pollutant loadings to the lake for phosphorus were calculated using unit
area loading rates, information developed as part of the Lake Carey TMDL, and the 1977
Reckhow Anoxic model.
6.1
Hydrologic Budget
A hydrologic budget for Lake Carey was estimated based on stream gauging stations and
information from similar watersheds. Hydrologic data from the Lackawanna Lake watershed was
used to estimate the annual base flow and the annual stormflow to Lake Carey. The Lackawanna
Lake watershed is similar in both geology and soil types to the Lake Carey watershed. Annual
base flow was estimated based on a flow rate of 1.46 cfsm, and the annual storm flow was
estimated based on a flow rate of 51.75 million gallons per square mile. The volume of rain that
falls on Lake Carey and other waterbodies in the watershed was calculated based on an annual
rainfall amount of 36.56 inches (NCDC 9705 – 1964 through 2003).
Lake Carey received approximately 324.3 million gallons of water during the 2003 study period.
The largest source of water to Lake Carey is from the Meade Brook subwatershed. Based on the
net total volume of water entering the lake and the lake’s volume, Lake Carey has a hydraulic
residence time of 0.479 years or 171 days.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
60
F. X. Browne, Inc.
6.2
Phosphorus Loadings
Phosphorus loadings to Lake Carey were estimated based on unit area loading rates and land
uses within the watershed. The total phosphorus load to Lake Carey from the watershed and from
direct precipitation is 2,612 pounds, as shown in Table 6.1.
Table 6.1
Phosphorus Loads to Lake Carey (not including internal loading and septic
system inputs
Percent of
UAL Rate
Loading Percent
Land Use
Acres
Watershed
(lb/acre/year) (lb/year) Load
Mixed
Agriculture
1788
43
1.01
1806
69
Mixed Forest
1828
44
0.21
384
15
Residential
201
5
1.70
342
15
Open Water
356
9
79
3
Totals
4173
100
2612
100
Internal loading and septic system inputs were estimated using the Reckhow Anoxic Model, as
described in the Phosphorus Modeling sections below.
6.3
Phosphorus Modeling
Phosphorus was identified as the probable "limiting" nutrient in Lake Carey based on the algal
assay testing that was conducted as part of this study. Therefore, it appears that phosphorus
controls the overall degree or level of eutrophication in the lake. However, at times, nitrogen
may also be limiting. Both phosphorus and nitrogen levels need to be controlled to significantly
improve the water quality of Lake Carey. Since phosphorus is the easiest nutrient to control, the
focus of this project is to determine the amount of phosphorus that needs to be removed from the
Lake Carey system to reduce the trophic state of the lake from hyper-eutrophic to borderline
eutrophic.
Simply stated, the amount of phosphorus found in the water column of a lake is a function of (1)
the amount of phosphorus entering the lake, (2) the amount of phosphorus flowing out of the
lake, and (3) the amount of phosphorus absorbed or released by the in-lake sediments. This
simple input-output principle has been used to develop a large number of models to predict the
lake phosphorus concentration if the input (load) and the basin's hydrology are determined. The
major difference between these models is the method of calculating the sedimentation term.
Since it is not practical to measure phosphorus sedimentation directly, it must be estimated
empirically based on a lake's morphometric and hydrologic characteristics.
Internal phosphorus loading occurs when the water in the hypolimnion is devoid of oxygen.
When anoxic (zero dissolved oxygen) conditions occur, the insoluble iron-phosphorus complex
in the lake sediment is reduced to a soluble iron-phosphorus complex, resulting in the release of
soluble phosphorus to the hypolimnetic waters. During the study, the dissolved oxygen
concentration in the hypolimnion was essentially zero during all of the sampling events, except
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
61
F. X. Browne, Inc.
for the May 2004 sampling event. A large volume of the hypolimnion was anoxic for most of the
growing season in Lake Carey; therefore, it is likely that phosphorus was released from the lake
sediments from June through October. In August of 2003, the total phosphorus was 0.889 mg/L
in the hypolimnion (bottom waters) and 0.071 mg/L in the epilimnion (surface waters). This
indicates that phosphorus was being released from the sediments since the bottom water had a
higher total phosphorus concentration than the surface water.
Most empirical lake phosphorus models are based on two assumptions. The first assumption is
that a lake behaves as a continuously stirred reactor, implying that phosphorus concentrations are
uniform throughout the lake. Since this is seldom true in lakes, it is necessary to sample a
number of locations and different strata (depths) to estimate the true lake phosphorus content.
The second assumption is that the lake is in steady state, meaning concentrations do not change
over time. In order to incorporate this assumption, it is important to sample a lake at different
times of the year to account for seasonal variations in total phosphorus concentration. Simple
empirical phosphorus models are commonly used and widely accepted as a method of predicting
lake response to watershed loading.
These models are most commonly used in lake management to predict the response of an
existing lake to a change in its phosphorus load. In these cases, one has the advantage of being
able to compare the actual current lake phosphorus concentration to the predicted concentration
during the model evaluation process. The model selected is then used to predict the impact of
changing the phosphorus load.
In this study, the calculated annual phosphorus budget, along with the physical characteristics of
Lake Carey, were used to select the most appropriate phosphorus loading model. Next, the
selected model was used to predict the in-lake phosphorus concentrations for the study period.
The predicted phosphorus concentration was compared to the actual in-lake phosphorus
concentration for the study period, and the difference in concentrations was attributed to internal
loading and septic system loading. Finally, the selected model was used to predict phosphorus
load reductions that would be necessary in order to reclassify Lake Carey as a borderline
eutrophic lake system.
6.3.1
Evaluation of Models
Numerous phosphorus models were evaluated for their applicability to Lake Carey. The most
critical stage in performing any modeling exercises is to select the most appropriate model. In
general, empirical phosphorus models should not be applied outside the bounds of the data set
used to develop the model (Reckhow 1980). The following models were evaluated for their
applicability to Lake Carey: Vollenweider (1969), Kirchner and Dillon (1975), Chapra (1975),
Larsen and Mercier (1976), Jones and Bachmann (1976), Canfield and Bachmann (1981), Prairie
(1989), Reckhow (1977) and Walker (1977).
After reviewing over fifteen models, the Reckhow Anoxic Model was selected as the most
appropriate model for Lake Carey. Nearly two-thirds of the models that were reviewed were
developed for lakes with low to moderate in-lake total phosphorus concentrations. These models
will tend to over-estimate the in-lake phosphorus concentration in phosphorus-rich lakes.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
62
F. X. Browne, Inc.
Secondly, the dissolved oxygen levels in Lake Carey become depleted during the summer
growing season, and therefore the internal release of phosphorus via lake sediments is expected
to be relatively high. The Reckhow Anoxic Model was developed from a database of lakes that
were classified as anoxic; hence its sedimentation coefficient tends to account for the high
internal release of phosphorus by sediments.
Reckhow lists two known constraints for his anoxic model and they are: (1) the in-lake
phosphorus concentration should range from 0.017 to 0.610 mg/L as phosphorus, and (2) the
phosphorus influent concentration should be between 0.024 and 0.621 mg/L as phosphorus. The
average total phosphorus concentration for the study period in Lake Carey was 0.340 mg/L as
phosphorus. The mean influent phosphorus concentration to Lake Carey was 0.067 mg/L as
phosphorus. Therefore, the average in-lake total phosphorus concentrations and influent
phosphorus concentrations are in good agreement with the known constraints of the Reckhow
Anoxic Model.
6.3.2
Modeling Results
The estimated phosphorus load from land uses and precipitation was input into the model to
predict the average in-lake concentration. The difference between the model prediction and the
actual value was assumed to be the amount of phosphorus that is being added to the lake from a
combination of septic systems and internal loading. The final phosphorus loading to Lake Carey,
including internal loading and septic system loading, is 4,784 pounds and is shown in Table 6.2.
Table 6.2
Total Phosphorus Pollutant Loading to Lake Carey
(including internal loading and septic system loading)
Percent of
UAL Rate
Loading Percent
Land Use
Acres
Watershed
(lb/acre/year) (lb/year) Load
Mixed Agriculture
1788
43
1.01
1806
37
Mixed Forest
1828
44
0.21
384
8
Residential
201
5
1.70
342
7
Open Water
356
9
79
2
Septic Systems &
2262
46
Internal Loading
Totals
4173
100
4874
100
6.4
Phosphorus Reduction Requirements
The Reckhow Anoxic Model was used to determine the reduction in phosphorus loading that is
required to bring Lake Carey to a borderline eutrophic level. The target in-lake concentration for
Lake Carey was assumed to be 0.030 mg/L. Based on this phosphorus criterion, a 70.5%
reduction in the total phosphorus load is required to reach mesotrophic conditions in Lake Carey.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
63
F. X. Browne, Inc.
7.0
Lake and Watershed Management Plan
7.1
Goals
In this report Lake Carey has been studied as two separate, but linked water bodies. There is the
larger, deeper, upper section referred to as the “lake”, and there is the smaller, shallower, lower
section referred to as the “pond.” Both are highly eutrophic; the pond can be classified as hyper
eutrophic.
The goals of this management plan are to protect Lake Carey from further degradation, and to
reduce the present eutrophic condition of Lake Carey to a mesotrophic condition, or, at the very
least, a less eutrophic condition. These goals are quantified in Table 7.1
Lake Classification
Total Phosphorus
Chlorophyll a
Blue-Green Algae
Table 7.1
Quantitative Water Quality Goals for Lake Carey
Present Condition
Goal
Eutrophic – Hypereutrophic
Border line Eutrophic
0.044 mg/l – 0.072 mg/l
0.025 – 0.030 mg/l
6 – 43 ug/l
6 – 10 ug/l
High, Dominant
Low, Non-Dominant
These goals can be realized by reducing the amount of nutrients (nitrogen and phosphorus) and
sediments entering Lake Carey. Specifically, these goals can be achieved by implementing a
program that consists of erosion and stormwater control, wastewater management, public
education, and the adoption of ordinances to properly manage any future growth. Except for
specific in-lake restoration measures, such as dredging or nutrient inactivation which are specific
for the “lake” or “pond”, the recommended management plan applies to all of Lake Carey, both
the “lake” and the “pond.”
7.2
Overview of Management Plan
An effective management plan must include both in-lake management practices and watershed
management practices. Due to the high amount of nutrients entering and present in Lake Carey,
however, the emphasis of the management plan should initially be placed on watershed
management, on reducing the nutrients and sediments entering Lake Carey. After the nutrient
and sediment loads to the lake are reduced, the emphasis of the management plan may shift to inlake management measures. Dredging of the “pond”, however, should be investigated during the
initial stages of the management plan since dredging of the unconsolidated sediments would
remove a significant amount of nutrients, resulting in a lowering of the internal phosphorus
loading.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
64
F. X. Browne, Inc.
The lake and watershed management plan consists of the following elements:
1.
2.
3.
4.
5.
Watershed Management
Wastewater Management
In-Lake Management
Public Education
Water Quality Monitoring
Each of these management plan elements are discussed in the following sections.
7.3
Watershed Management
Managing the Lake Carey watershed is the key to reducing the excessive sediments entering
Lake Carey. It is also important for reducing the nutrient loading to Lake Carey. As discussed in
Section 4.0, Lake Carey has very high concentrations of phosphorus and nitrogen; it also has
large volumes of unconsolidated sediments (1.2 million cubic yards in the lake and 291,200
cubic yards in the pond). In-lake treatment measures such as phosphorus inactivation and
aeration will not be effective until the nutrient and sediment loadings to Lake Carey are
significantly reduced.
The watershed management program should consist of the following:
1.
Control of Existing Erosion and Stormwater Runoff,
2.
Control of New Development and Related Erosion and Stormwater
Runoff, and
3.
Control of Erosion and Stormwater Runoff from Agricultural Activities
Each of these management plan elements are discussed in the following sections:
7.3.1
Control of Existing Erosion and Stormwater Runoff
The main source of the siltation of Lake Carey is soil erosion and stormwater runoff. Much of
the siltation of the lake appears to have been caused by erosion and stormwater runoff during and
after construction from existing residential and commercial buildings, roads, parking lots,
driveways, unvegetated areas, and tree removal. Control of soil erosion and stormwater runoff
from existing areas of the watershed can be accomplished by retrofitting existing problem areas,
implementing homeowner practices, installing shoreline and streambank vegetated buffers, and
mitigating erosion and stormwater runoff from existing dirt and gravel roads.
Retrofitting Existing Problem Areas
Section 5.0 – Watershed Evaluations identified a variety of erosion and stormwater runoff
problems throughout the Lake Carey Watershed. The watershed problem areas identified in
Section 5.0 should be corrected. These problem areas consist of roads, culverts, gullies, drainage
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
65
F. X. Browne, Inc.
ditches, driveways, and unvegetated lakeshore areas that contribute eroded soil and polluted
stormwater to Lake Carey.
The best method to control erosion and polluted stormwater runoff from these areas is specific to
each site. In general, however, the basic stormwater management practices that are applicable to
the Lake Carey watershed consist of the following:
1.
Maximize the use of natural bioengineering methods that use vegetation
and retention to slow down the stormwater runoff, retain the runoff,
reduce soil erosion, and filter pollutants from the runoff,
2.
Minimize the use of impervious surfaces and storm sewers to transport
untreated, polluted runoff to Lake Carey,
3.
Where storm sewers are used, direct the stormwater over vegetated areas,
not directly to streams or Lake Carey, and
4.
Vegetate areas along roadways and commercial establishments to reduce
soil erosion.
This report identifies many nonpoint source problem areas. Most of these are public areas around
the watershed. There are, however, many private areas that have significant erosion and
stormwater runoff problems. Many of the homes in the watershed are located on small, steepsloped, highly impervious lots. An important element of the management plan, therefore, should
be to inform homeowners and commercial establishments about erosion and stormwater
problems and provide information that will help them correct and retrofit problem areas on their
home and commercial sites.
Homeowner/Commercial Site Practices
Homeowners and owners of commercial establishments should be encouraged to implement
environmentally-friendly practices on their sites. The following practices should be encouraged:
1.
Keep site disturbance to a minimum, especially avoid the removal of
natural vegetation and the exposure of bare soil,
2.
Seed and mulch any bare soil in the yard and especially near shoreline
areas to prevent loss of soil during rain storms,
3.
Leave naturally vegetated areas along the lake shore, streams, and road
ditches,
4.
Plant deep rooted woody, native vegetation along lake shores, streambeds
and road ditches,
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
66
F. X. Browne, Inc.
5.
Minimize the use of herbicides, pesticides and fertilizers on yards and
gardens,
6.
Stabilize steep slopes with ground cover, mulches or stone,
7.
Create a “buffer zone” of natural vegetation between buildings and the
water. Trees, grasses, and shrubs will stabilize shorelines. If ground has
been disturbed, place an erosion barrier such as straw bales at the bottom
of the slopes. This will retain sediments while ground cover is being reestablished, and
8.
Do not cut down trees unless absolutely necessary. Trees provide many
environmental benefits including soil stabilization, nutrient uptake, and
evapotranspiration of stormwater.
Most homeowners and owners of commercial establishments do not realize that they should be
implementing these practices. Implementation of these practices can best be accomplished by
including a description of these practices in fact sheets, newsletters and websites as part of the
public education program recommended in Section 7.7.
Shoreline and Streambank Vegetative Buffers
Shoreline landscaping affects the condition of Lake Carey. The most common shoreline
landscape around Lake Carey is a lawn planted with grass leading to the shoreline or a bulkhead.
There are several problems with this type of landscaping. Grass lawns do not effectively filter
nutrients, such as phosphorus, from stormwater runoff. In fact, the use of fertilizers on grass
lawns increases the amount of nutrients entering Lake Carey. Vegetated buffers of native plant
species should be encouraged for the shoreline of Lake Carey and for the tributary streams of
Lake Carey.
Vegetative buffers have the following advantages:
1.
Emergent vegetation in the lakes, like bulrushes and cattails, reduce
shoreline erosion caused by wind and boat traffic,
2.
Natural vegetation along the shoreline serves as a filter that helps prevent
sediment, nutrients, fertilizers and pesticides from entering the lake,
3.
Vegetative buffers reduce the amount of fertilizers and herbicides needed
on a shoreline property because the resulting lawn is smaller, and native
plants in the buffer zone do not need fertilizers or herbicides, and
4.
Unmowed wildflowers, grasses, and sedges along the shore create a
biological barrier that will deter Canada geese.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
67
F. X. Browne, Inc.
Streambank Stabilization
Erosion is one of the major sources of nonpoint source pollution in watersheds. Certain
nutrients as well as many other “pollutants” adhere to eroded soil particles and are
transported to the streams and to Lake Carey. Several streams flowing into Lake Carey
have eroded streambanks and lack adequate vegetation. It is likely that other areas of
streambank erosion exist along the tributaries on private land that could not be inspected
as part of this project.
Restoration of eroded streambanks is a cost-effective way to significantly reduce
sediment and nutrient loadings to Lake Carey. By using bioengineering (vegetative) or a
combination of bioengineering and structural engineering streambank stabilization
techniques, the erosion problem can be corrected while the stabilized streambank can
serve as a vegetative buffer and, in many cases, a restored riparian corridor. Riparian
buffers along the streams will reduce the quantities of sediments and nutrients that enter
the streams via stormwater runoff.
A variety of methods are designed to stabilize eroded streambanks and reduce continued
erosion and sedimentation. Some methods reduce the amount and velocity of water in the
stream, others involve relatively high cost structural controls such as rip-rap and gabions,
and still others involve relatively low-cost controls such as willow twigs, grasses, shrubs,
or wetland vegetation. Lower cost, bioengineering approaches should be used wherever
practical to stabilize the severely eroded streambank areas noted on the nonpoint source
problem area map. Where warranted, a structural stabilization element should be included
in the overall project design to ensure long term stabilization and to provide adequate
protection against high streamflows and high flow velocities.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
68
F. X. Browne, Inc.
Gravel Roads
There are three gravel roads on private property in the Lake Carey watershed that are located on
very steep slopes. These roads contribute sediment and nutrients to Lake Carey due to transport
of polluted stormwater to Lake Carey and the erosion of the roads.
The solution for each road is similar. As shown in Figures 7.1 to 7.3, Roads 1 through 3 all need
the same basic solution:
1.
The roads should be paved to eliminate soil and gravel erosion from each
road.
2.
When the roads are paved, they should be sloped so that stormwater runoff
drains to the sides of the roads and into vegetated areas where the
stormwater will be slowed down, filtered, and infiltrated.
3.
Bioretention-Swale Treatment Systems should be constructed on the lake
side of each road as shown on Figures 7.1 to 7.3. A schematic of the
Bioretention-Swale is shown in Figure 7.4. Stormwater from the paved
roads will flow over the road and into the Bioretention-Swale System. The
rock-lined forebay will remove the larger particulate matter before
stormwater flows into the vegetated bioretention system where stormwater
will be stored, filtered, and infiltrated. Treated stormwater will discharge
from the Bioretention System into a grass swale which will further filter
the stormwater before it reaches the lake.
Road 1 has an existing storm culvert under the road. Stormwater runoff from the culvert should
be directed to the Bioretention-Swale Treatment System.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
69
F. X. Browne, Inc.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
70
F. X. Browne, Inc.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
71
F. X. Browne, Inc.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
72
F. X. Browne, Inc.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
73
F. X. Browne, Inc.
7.3.2 Control of New Development and Related Erosion and Stormwater
Runoff
Much of the present siltation of Lake Carey occurred years ago when houses, roads, and other
infrastructure were constructed prior to the restrictive erosion and sedimentation regulations and
controls presently being enforced. If properly designed and inspected, present day erosion and
sediment control plans should protect Lake Carey from excessive siltation. The best strategy, of
course, is prevention; new construction within the lake’s watershed should be minimized.
When new development is proposed, controlling soil erosion and stormwater runoff during
construction and after construction is critical. If not properly controlled, they will be a significant
source of additional nutrients and sediment to Lake Carey. In fact, uncontrolled construction
activities produce one of the highest pollutant loads to any waterbody. Construction of
individual homes does not always require an erosion and sedimentation plan and its review. The
township ordinances should be amended to require the development and review of such plans for
all earthmoving and building activities.
The long-term erosion and stormwater runoff caused by new development is a matter of even
greater concern. Unlike erosion from construction activities which only lasts during the
construction period, erosion and stormwater runoff from post-construction development lasts
forever. New development produces more impervious areas such as buildings, driveways,
parking lots, and roads. Impervious surfaces cover soils that once infiltrated stormwater into the
groundwater. Impervious surfaces, therefore, cause nonpoint source pollution in a variety of
ways:
1.
Impervious areas significantly increase the peak rate, velocity and volume
of stormwater runoff.
2.
Runoff from impervious areas washes pollutants such as nutrients,
sediments, and bacteria into streams and lakes.
3.
Runoffs from impervious areas have a higher temperature than pervious
areas. The higher temperature can adversely affect the plant and animal
life in streams and lakes, and
4.
The larger volume and higher velocity of stormwater runoff from
impervious surfaces causes soil erosion, shoreline erosion, and streambank
erosion.
To address these serious threats to the future of Lake Carey, the landowners within the lake’s
watershed should be encouraged to grant conservation easements, especially on properties with
sensitive areas such as wetlands, streams, and lake shorelines. To minimize the adverse impacts
of stormwater runoff from any new development, the townships should adopt the following new
ordinances: riparian buffer, conservation and stormwater management. In addition, the existing
Zoning Ordinance should be revised.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
74
F. X. Browne, Inc.
Conservation Easements
Conservation Easements help preserve open space, protect critical areas from development, and
concentrate development in areas that are already disturbed. A conservation easement is a
voluntary agreement that allows a landowner to limit the type or amount of development on their
property while retaining private ownership of the land. The easement is signed by the landowner,
who is the easement donor, and a land trust or conservancy, who is the party receiving the
easement. The easement applies to all future owners of the land. By granting a conservation
easement a landowner can assure that the property will be protected from unwanted development
forever, while maintaining ownership of the land. An additional benefit of granting a
conservation easement is that the donation of an easement may provide significant financial
advantage to the donor.
Residents of the Lake Carey watershed who own land within the watershed, especially in critical
areas such as lake shorelines, wetlands, and riparian areas around streams, should be encouraged
to develop conservation easements to protect the property against future development. The
development pressure is extremely high in the watershed, but if protective measures are in place,
the sensitive areas can be protected. The Lake Carey Cottages Association should continue to
work with the Countryside Conservancy and North Branch Land Trust to offer workshops for
watershed residents on conservation easements.
Riparian Buffer Ordinance
A riparian buffer ordinance should be adopted to require buffers along wetlands, streams, and
lake and pond shorelines for all new construction projects. A buffer of approximately 75 feet
should be sufficient to protect water quality along wetlands and streams. A 50-foot buffer is
more realistic for lake and pond shorelines. The purpose of the riparian buffer would be to (1)
eliminate major earthmoving activities close to the stream, and (2) to filter and infiltrate
stormwater runoff before it reaches the water.
Conservation Ordinance
A conservation ordinance should be adopted to require developers to identify all environmentally
sensitive areas on a site including wetlands, trees, waterbodies, slopes, and soils. An alternative
to adopting a separate ordinance would be to include these provisions in the stormwater
management ordinance.
Stormwater Management Ordinance
A stormwater management ordinance should be adopted by both townships to control nonpoint
source pollution from future development. The stormwater management ordinance should
incorporate the Part II NPDES requirements that the 2-year storm be managed for runoff volume
and water quality. The stormwater ordinance should refer to the new Pennsylvania DEP Best
Management Practices (BMP) Manual and require its use in all new development. The
stormwater ordinance in conjunction with the DEP BMP Manual should require that low impact
development concepts be incorporated into all new development plans. Low impact development
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
75
F. X. Browne, Inc.
is an innovative, ecosystem-based approach to land development and stormwater management.
The general goals of low impact development are to reduce the amount of impervious area on a
site and to infiltrate and treat stormwater runoff. Low impact development mimics the predevelopment hydrology and controls the peak flow, volume, and quality of stormwater runoff. It
does this by minimizing the effective impervious area (the impervious area that produces
stormwater runoff) and directing stormwater runoff onto vegetated areas that treat, infiltrate, and
evaporate the runoff.
The primary planning concepts of low impact development include the following:
1.
Maintain-improve the site hydrology,
2.
Control stormwater at the source,
3.
Use a variety of small BMPs rather than one or more large detention
basins,
4.
Maximize the use of natural, non-structural control methods,
5.
Minimize the use of storm sewers, and
6.
Create a multifunctional environment that includes stormwater control and
treatment, habitat for wildlife, and aesthetics.
Case studies of low impact development around the country have shown that these developments
reduce stormwater volume, protect water quality, provide greener developments, and are costeffective.
Zoning Ordinance
The existing zoning ordinance should be revised to incorporate the significant elements of the
stormwater management ordinance and low impact development concepts. Specific areas of the
zoning ordinance that may need revision include:
1.
Housing density,
2.
Setbacks and yard lines,
3.
Road widths,
4.
Cul-de-sac lengths,
5.
Curb and gutter, and
6.
Stormwater detention requirements.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
76
F. X. Browne, Inc.
It is important that all of the municipal ordinances work together and do not conflict with each
other.
7.3.3
Control of Erosion and Stormwater Runoff from Agriculture
There are approximately 1793 acres of agricultural land in the Lake Carey watershed. This
accounts for about 43 percent of the watershed. Agricultural land contributes approximately 38
percent of the annual phosphorus load to Lake Carey.
According to the “Total Maximum Daily Loads (TMDLs) – Lake Carey, Wyoming County”
report developed by the Susquehanna River Basin Commission (2001), agricultural runoff in the
watershed has been largely reduced through best management practices promoted by the
Wyoming County Conservation District. The report indicates that the agricultural management
practices have been recently implemented, but that no monitoring was performed to assess the
effectiveness of the control measures. The Lake Carey Cottages Association should meet with
the National Resource Conservation Service (NRCS) periodically to discuss the progress of
implementing agricultural BMPs and whether or not the BMPs are operating properly.
The NRCS and the Wyoming County Conservation District should continue to work with the
farmers to ensure that agricultural best management practices are applied to all the agricultural
land in the watershed. They should work with the farmers to ensure that all active farms have an
up-to-date conservation plan and nutrient management plan that is being implemented.
7.4
Wastewater Management
It is estimated that the phosphorus loading from septic systems and internal loading is 2196
pounds per year. This accounts for 46 percent of the annual loading. Although it is not possible
to calculate a specific, separate loading for septic systems, it is probable that a significant amount
of the 2196 lbs/year is being contributed by failing septic systems.
As shown in Figure 7.5, a septic system needs several feet of dry soil to properly renovate or
treat the septic tank effluent. If the seasonably high groundwater is at or above the level of the
septic system drainfield, the septic tank effluent will not receive proper treatment and it will
flow, untreated, into the groundwater and ultimately into Lake Carey. Figure 7.6 depicts the soils
in the Lake Carey watershed that are suitable for conventional septic systems. As shown in
Figure 7.6, all of the soils in the watershed have severe restrictions for conventional septic
systems. This indicates that there is a high probability that all of the conventional septic systems
in the Lake Carey watershed are failing and are polluting the groundwater and Lake Carey. Due
to the high contribution of both phosphorus and nitrogen by septic systems, a wastewater
management program should be implemented in the Lake Carey watershed, and this program
should be a high priority.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
77
F. X. Browne, Inc.
Figure 7.5 Conventional Septic System
There are several wastewater management options that should be considered:
1.
On-Site Wastewater System Solutions,
2.
Decentralized Wastewater System Solutions
3.
Centralized Wastewater System Solutions
Each of these management options are discussed in the following sections.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
78
F. X. Browne, Inc.
Figure 7.6 Suitability of Soils in the Lake Carey Watershed for Septic Systems
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
79
F. X. Browne, Inc.
7.4.1
On-Site Wastewater System Solutions
On-site solutions to failing septic systems usually include one or more of the following:
1.
Implement a Septic System Management Program that requires regular
pumping of the septic tank,
2.
Repair failing septic systems, and
3.
Replace failing septic systems.
Septic System Management Program
Regular pumping of the sludge in the septic system only works if the septic system is
properly located, designed, and constructed. According to Figure 7.6, none of the soils in
the watershed is suitable for a conventional septic system. Most of the septic systems in
the watershed are conventional systems or sub par systems that do not meet present
standards. These include 55 gallon drums, cesspools and undersized systems.
The septic systems in the Lake Carey Watershed are failing because they never should
have been constructed. The high seasonal groundwater in much of the area precludes the
proper operation of the septic systems. Conventional septic systems would not be
approved under present DEP regulations in most of the watershed. Therefore, a septic
system management program is not a viable solution for most of the existing
conventional septic systems.
Repair Failing Septic Systems
The septic systems are not broken; therefore, they cannot be repaired. As discussed
above, the soils in the Lake Carey Watershed are not suitable for conventional septic
systems. Therefore, repair of failing septic systems is not a viable solution.
Replace Failing Septic Systems
Figure 7.7 shows soils in the watershed that may be suitable for other types of on-side
methods, such as drip irrigation, mound systems, and spray irrigation. It may be possible,
therefore, in some cases to abandon the failing septic system and replace it with a nonconventional system. Soil testing consisting of a pit test and hydroconductivity test would
have to be performed on each site to determine whether the site would be suitable for a
non-conventional system.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
80
F. X. Browne, Inc.
Figure 7.7 Suitability of Soil for Drip, Spray & Mound Treatment Systems Based
On Groundwater Level and Slope
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
81
F. X. Browne, Inc.
Replacement of a failing septic system with a non-conventional system has several problems and
limitations:
1.
Availability of suitable soil,
2.
Availability of space on the site,
3.
Proximity to water supply,
4.
Expense of replacement system,
5.
Maintenance of replacement system, and
6.
Lack of statutory authority.
Many of the lots in the watershed are small; therefore, it is highly improbable that sufficient land
with a suitable soil at a proper distance from a water supply well will be available for most
homes. Some of these non-conventional systems are expensive to design and build. Some of
them, especially spray irrigation, requires a significant amount of regular maintenance. A major
drawback to replacement of failing septic systems is the lack of statutory authority by the
townships and others to require that a septic system be replaced. A municipality or other agency
would have to have clear proof that a specific system was failing and polluting a stream, lake or
water supply.
Replacement of failing septic system, therefore, is not a long-term, watershed-wide feasible
solution to failing septic systems.
7.4.2
Decentralized Wastewater
A decentralized wastewater system, also known as a community cluster system, is defined by
EPA as “An onsite or cluster wastewater system that is used to treat and dispose of relatively
small volumes of wastewater, generally from individual or groups of dwellings and businesses.”
A comparison of a centralized vs. decentralized system is presented in Figure 7.8. The
centralized wastewater system uses gravity or pressure sewers to transport all of the wastewater
in the area to one location for treatment and disposal, usually to a stream.
The decentralized wastewater system consists of a variety of clusters where wastewater from
each cluster is transported to a smaller wastewater system for treatment and disposal. A
decentralized wastewater system separates the service area into clusters, and the wastewater from
each cluster is transported to and treated at a separate treatment facility. Instead of one
centralized treatment facility, there are two or more smaller, decentralized wastewater treatment
facilities. The cluster treatment system, being smaller due to the reduced cluster wastewater flow,
may be an on-site system such as a mound, drip system, or spray irrigation system. It could also
be a small package treatment plant that discharges to a stream.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
82
F. X. Browne, Inc.
There are several advantages to a decentralized wastewater system:
1.
Decentralized systems can be used to control growth,
2.
Decentralized systems usually do not promote uncontrolled growth like
centralized systems often do,
3.
Decentralized systems often are less expensive to construct and operate.
They often reduce the length of sewers needed and do not sewer
unpopulated areas,
4.
Decentralized systems, consisting of a series of smaller wastewater flows,
have a greater potential for on-site disposal. Most centralized wastewater
systems require a wastewater treatment plant with stream discharge
because of the larger wastewater flows being treated, and
5.
If on-site treatment and disposal is feasible, centralized systems, by using
on-site soil disposal, provides better treatment, better meets EPA and DEP
water quality antidegradation requirements, and recharges groundwater.
There are, however, several disadvantages to decentralized wastewater systems. They usually
require more up-front soils testing to locate suitable sites. They may also require slightly higher
engineering design fees. Although system maintenance would probably be lower than a
centralized system, it could be more complicated due to the multiple cluster systems.
In their report entitled “Response to Congress on Use of Decentralized Wastewater Treatment
Systems”, EPA indicated concern about the gap between wastewater needs and available federalstate funding. The report indicated there is a need to identify and implement alternatives to costly
centralized treatment and collection systems. The conclusion of the EPA report is that
“adequately managed decentralized wastewater systems are a cost-effective and long-term option
for meeting public health and water quality goals.”
Community wastewater systems can consist of gravity sewers, high pressure sewers, or low
pressure sewers. They can use grinder pumps or pump stations to transport wastewater to the
treatment facilities.
Grinder pumps are used to pump raw wastewater into a gravity sewer or pressure sewer. A pump
station usually receives wastewater from gravity sewers and pumps the raw wastewater to the
treatment facility through pressure sewers. An innovative alternative to grinder pumps and pump
stations is the STEP system (Septic Tank Effluent Pump). In a STEP system, as shown in Figure
7.5, a small tank with a sump pump is attached to the outlet of the existing septic tank (the septic
tank is disconnected from the existing drainfield). Septic tank effluent flows in the attached tank
where the sump pump pumps it to a small diameter presser sewer. The pressure sewer transports
the partially treated wastewater to the treatment facility.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
83
F. X. Browne, Inc.
The STEP system has the following characteristics:
1.
The existing septic tank is used to settle the raw wastewater.
2.
Only the effluent from the septic tank is treated at the treatment facility.
3.
Sludge must be removed from the septic tank every 2 to 3 years.
STEP systems usually have construction costs that are significantly lower than conventional
systems since they are inexpensive sump pumps and small diameter pressure sewers.
The treatment/disposal system can be soil-based such as a mound, drip system, or spray
irrigation. It also could be a small package treatment plant with a discharge to a stream. It could
be a combination of the above.
Decentralized wastewater systems should be investigated as part of a joint township Act 537
Wastewater Management Plan revision.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
84
F. X. Browne, Inc.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
85
F. X. Browne, Inc.
7.4.3
Centralized Wastewater System
A centralized wastewater system consists of a centralized wastewater collection system that
transports all of the wastewater from an area to a central wastewater treatment facility. Due to
the normally high wastewater flows from a centralized sewer system, the treatment facility is
usually a wastewater treatment plant with stream discharge.
Like a decentralized system, a centralized system can consist of gravity, high pressure and low
pressure sewers. It could consist of grinder pumps, STEP systems, or pump stations.
Due to the larger size of a central wastewater treatment facility, more treatment system options
would be available. Besides the conventional extended aeration treatment plant, other treatment
options would include the sequential batch reactor (SBR), the oxidation ditch process, and the
phased isolation ditch, an innovative combination of the SBR and oxidation ditch.
There are several concerns associated with a centralized wastewater system:
1.
The system construction costs could be higher than a community
decentralized system primarily due to the larger collection system,
2.
Finding a site suitable for spray irrigation or other form of soil disposal
may not be possible given the poor soil conditions in the watershed,
3.
Due to the latest DEP antidegradation policies and regulations, a stream
discharge may not be economically feasible. The new antidegradation
policies require that all sites capable of on-site disposal must use on-site
disposal, even if a sanitary sewer runs adjacent to the property,
4.
A centralized wastewater system would probably promote growth around
Lake Carey and in other areas of the watershed. Revisions to the zoning
ordinance may provide better growth management in some areas,
however, in developed areas around the lake there are many approved lots
that would be grandfathered into previous zoning regulations, and
5.
A centralized system with stream discharge will reduce the existing
groundwater recharge and lead to a lowering of the groundwater table.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
86
F. X. Browne, Inc.
7.4.4
Act 537 Plan Revision
The present Act 537 Wastewater Management Plan should be revised to incorporate the
evaluation of the following alternatives:
1.
Community Decentralized Systems,
2.
Centralized Systems, and
3.
Combination Systems
The Act 537 Wastewater Management Plan should look at all the options discussed above:
cluster systems, different types of sewers, STEP systems, on-site disposal, (mound systems, drip
irrigation systems, spray irrigation systems, etc.), centralized systems, and alternative treatment
facilities.
The Wastewater Management Plan should evaluate all aspects of the various systems including
capital and operating costs, permitting requirements, impacts on streams and Lake Carey, and
impacts on groundwater quality and level.
7.5
In-Lake Management
In-lake management practices that should be considered include:
1.
Lake Dredging
2.
Lake Aeration
3.
Phosphorus Inactivation
These in-lake management practices are discussed in greater detail in the following sections.
7.5.1
Lake Dredging
Lake
The “lake” section of Lake Carey has a mean depth of 18.4 feet and a mean sediment depth of
4.1 feet. Although the lake has a significant accumulation of unconsolidated sediments (1.2
million cubic yards), dredging of the lake is not recommended because (1) there is sufficient
water depth in the lake, and (2) dredging of 1.2 million cubic yards of sediment would be cost
prohibitive. The cost for dredging all of the unconsolidated sediments in the lake would range
from $10,000,000 to $30,000,000.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
87
F. X. Browne, Inc.
There are some shallow areas along some of the shoreline. These areas should be spot dredged if
they are a major problem for boating or other recreational activities. Spot dredging of select
shallow areas of the lake, however, will have very little effect on improving water quality in the
lake.
Pond
The “pond” section of Lake Carey has a mean depth of 3 feet and a mean sediment depth of 2.6
feet. Dredging of the pond would have several benefits. It would increase the water depth and
capacity of the pond; it would remove a significant amount of nutrients; and, by removing the
nutrients in the sediment, it would significantly reduce the internal loading of phosphorus to the
pond.
Based on historical dredging costs, costs for dredging of the 291,200 cubic yards of
unconsolidated sediments would range from $2,500,000 to $9,000,000. These costs are based on
projects that required formal public bidding. The dredging costs could be significantly lower if
the lake was drawn down and a local contractor was used to excavate the sediments. Dredging
costs vary based on a variety of factors, including:
1. The volume of unconsolidated sediment. The unit cost per cubic yard
decreases as the sediment volume increased.
2. The chemical composition of the sediment. If the sediment contains toxic or
hazardous chemicals in high concentrations, special disposal sites would be
required, significantly increasing the cost of dredging.
3. The location of the sediment disposal site. Dredging costs increase as the
distance to the sediment disposal site increases.
4. The physical characteristics of the sediment. If the sediment has
characteristics of top soil, some contractors may dredge the lake for a
significantly reduced price because he could use the sediment on construction
projects. In one dredging project where the contractor wanted the sediment,
the dredging cost was reduced to $2 per cubic yard. If the sediment is very
mucky and consists of a lot of organic matter, contractors will usually not be
interested in this kind of sediment, although it has a high nutrient content.
Dredging of the pond should be further investigated via a Dredging Feasibility Study. The study
should include an evaluation of dredging methods, sediment disposal locations, permitting
requirements and project costs.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
88
F. X. Browne, Inc.
7.5.2
Lake Aeration
Lake
Dissolved oxygen depletion is a major problem in the lake. During the summer months low or
depleted dissolved oxygen concentrations were observed. For example, in July 2004 the
dissolved oxygen was totally depleted from a depth of 5 meters to the bottom. In August 2003
the dissolved oxygen was depleted from a depth of 4 meters to the bottom.
Dissolved oxygen depletion adversely affects the lake by (1) significantly reducing the habitat
for fish, most of which need about 5 mg/l of dissolved oxygen to survive, (2) eliminating the
benthic macroinvertebrates (bottom aquatic insects), which are food for many fish, and (3)
releasing dissolved orthophosphorus from the sediments under anoxic conditions.
There are two types of lake aeration: total lake aeration and hypolimnetic aeration. Total lake
aeration consists of installing aerator tubing in the bottom of the lake. Air is pumped through the
tubing and enters the lake via small holes in the tubing. This type of aeration breaks up the
thermocline and allows the nutrient-laden bottom waters mix with the top waters of the lake.
Mixing of the nutrient-rich bottom waters with the surface waters would increase the
eutrophication of the lake. Total lake aeration, therefore, is not recommended.
The second type of lake aeration is hypolimnetic aeration. Hypolimnetic aeration consists of
adding air or oxygen to only the hypolimnion (bottom water below the thermocline) of the lake.
The purpose is to aerate only the bottom water where dissolved oxygen depletion occurs.
Hypolimnetic aeration, unlike total lake aeration, does not destratify the lake.
Hypolimnetic aeration should be investigated after a wastewater management system is installed
and the lake does not respond sufficiently to the removal of nutrients from septic systems.
Nutrients from septic systems and residential erosion should be controlled first. Lake monitoring
should be performed to evaluate the improvement in water quality. If more input is required,
hypolimnetic aeration should be further investigated.
Pond
Dissolved oxygen depletion does not occur in the pond due to the shallow condition. Aeration of
the pond is therefore not recommended.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
89
F. X. Browne, Inc.
7.5.3
Phosphorus Inactivation
Phosphorus inactivation is a lake restoration process that inactivates phosphorus so that it is not
available for biological uptake by the phytoplankton. There are two general types of phosphorus
inactivation: batch alum treatment and continuous alum treatment.
Batch Alum Treatment
Batch alum treatment consists of applying high doses of alum (aluminum sulfate) to the surface
of a lake. The alum falls to bottom of the lake where it reacts with phosphorus to form an
aluminum-phosphorus precipitate that effectively seals the bottom sediments. The purpose of
batch alum treatment is to seal the sediments so that phosphorus is not released during anoxic
conditions. Under the proper conditions, one alum treatment may last eight years or more. Batch
alum treatment is appropriate for lakes with high internal phosphorus recycling and low external
phosphorus loads. Since Lake Carey has a high external phosphorus load, batch alum treatment
is not appropriate at this time. If, after septic system and stormwater runoff nutrient loads are
reduced, the lake is still too eutrophic, then batch alum should be considered for both the lake
and pond.
Continuous Alum Treatment
Continuous alum treatment consists of adding alum directly to the major tributary (or tributaries)
of a lake on a continuous basis. The purpose of continuous alum treatment is to remove
phosphorus from the water entering a lake. Alum is added to the stream in proportion to the flow.
Alum jar tests were performed during this study to determine the dose needed to reduce the
phosphorus concentration to a sufficient level. The results of the alum jar tests indicated that an
alum dosage of about 68 mg/l was sufficient to reduce the phosphorus concentration to 0.008
mg/l. This indicates that continuous alum treatment would effectively reduce the phosphorus
load entering Lake Carey from Meade Brook, the major tributary.
Continuous alum treatment should be further evaluated after progress has been made on reducing
the phosphorus loading from failing septic systems. If the lake is still too eutrophic, then
continuous alum treatment may also be needed.
7.6
Public Education
Public education is an important component of an effective management plan. The Lake Carey
Cottages Association has been conducting a public education program for two years under a
Growing Greener Grant. The current program includes a newsletter, distribution of PALM
Notes, and summer public lectures. The program focuses on such topics as septic system
management, riparian buffers, well water safety, and lake ecology.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
90
F. X. Browne, Inc.
The Lake Carey public education program should be expanded to include coverage of the
following topics:
1.
Stormwater Impacts on Lake Carey,
2.
Stormwater Management and Low Impact Development,
3.
Wastewater Management Options,
4.
Agricultural Best Management Practices,
5.
Homeowner Practices, and
6.
Lake and Watershed Management Plan
The education program should consist of fact sheets, displays, workshops, and school programs.
The audience for the public education program should include landowners and businesses in the
watershed, lake users, elected and appointed municipal officials, developers, farmers, and school
students. A website should be developed so that the management plan and educational
information can be posted. Many of these activities can be funded by grants from the Growing
Greener Program.
7.7
Water Quality Monitoring
A modified water quality program should be continued. It should consist of lake and stream
monitoring. Lake Carey should be monitored once per month from May through September. One
station should be in the lake and one in the pond. A surface water sample should be collected
from each lake station and analyzed for the following parameters:
Total Phosphorus
Dissolved Reactive Phosphorus
Total Nitrogen
Chlorophyll a
Total Suspended Solids
pH
Phytoplankton
In situ measurements should include Secchi Disk and a temperature-dissolved oxygen profile at
each station.
Quarterly dry and wet weather stream samples should be collected and analyzed for total
suspended solids, total phosphorus, and total nitrogen.
A formal baseline macrophyte survey should be conducted by a professional ecologist in order to
document the macrophyte species present and determine whether any of those macrophytes are
non-native, invasive species. If any invasive species are found, steps should be taken to eradicate
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
91
F. X. Browne, Inc.
them immediately. Members of the Lake Carey Cottages Association should receive training in
the identification of the types of macrophytes found in Lake Carey as well as potential invasive
species so that they can conduct annual macrophyte surveys at the lake and pond. If in the future
the macrophyte populations become excessive, the Lake Carey Cottages Association should hire
a macrophyte management company to address the problem.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
92
F. X. Browne, Inc.
8.0
Implementation of Lake and Watershed Management Plan
8.1
Watershed Management Implementation
The two main priorities in watershed management for the Lake Carey watershed are managing
the damaging consequences of development: wastewater and stormwater. Implementing a
wastewater management program in the Lake Carey watershed should be a high priority.
Because the soils in the Lake Carey watershed have severe restrictions for conventional septic
systems, there is a high probability that all of the conventional septic systems in the Lake Carey
watershed are failing and are polluting the groundwater and Lake Carey. Therefore, replacement
or repair of the existing on-site wastewater systems is infeasible on a watershed scale.
Wastewater alternatives such as decentralized or centralized wastewater systems should be
evaluated as part of an Act 537 Plan revision for townships within the watershed.
The watershed stormwater problem areas identified in Section 5.0 should be corrected. These
problem areas consist of roads, culverts, gullies, drainage ditches, driveways, and unvegetated
lakeshore areas that contribute eroded soil and polluted stormwater to Lake Carey. Restoration of
eroding streambanks and installation or repair of drainage structures are highly successful ways
to significantly reduce sediment and nutrient loadings to Lake Carey for a reasonable cost. A
particularly low cost method for improving water quality in lakes and streams is to plant or
maintain a one to two foot unmowed vegetative buffer strip along all lake shores and
streambanks to ensure proper erosion control and to reduce the amount of nonpoint source
pollution entering the waterways.
The three problematic gravel roads in the Lake Carey watershed as noted in Section 7.3.1 should
be paved. Runoff from these roads should be directed to bioretention systems rather than to
storm sewers that discharge directly to Lake Carey.
Agricultural lands contribute significant amounts of sediment and nutrients to Lake Carey;
however, the Wyoming County Conservation District and the USDA Natural Resource
Conservation Service (NRCS) have already implemented many agricultural BMPs in the
watershed. These agricultural BMPs should be monitored to determine their effectiveness.
Nutrient Management and Conservation Management Plans are a high priority and should be
developed for all farms within the watershed. Riparian buffer zones on farmlands should be
restored as necessary to create a shrub and forested riparian zone along the tributaries to Lake
Carey. Farmer education and participation in the implementation of agricultural BMPs is
desirable since this practice will promote stewardship in the BMP. BMPs must be implemented
and maintained by the individual farmers in order to achieve the maximum benefit of the BMP.
8.2
Watershed Planning and Education Implementation
The Lake Carey watershed is developing rapidly. In order to preserve open space and protect the
water quality in Lake Carey, the townships in the watershed should update their zoning
ordinances and adopt riparian buffer, conservation, and stormwater management ordinances in
the near future. The existing public education program in the watershed should be expanded.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
93
F. X. Browne, Inc.
Local citizens should be educated about watershed protection practices and homeowner practices
that can help reduce nonpoint source pollution entering the lakes and streams.
8.3
In-Lake Management Implementation
In-lake management practices that should be considered for the pond and lake at Lake Carey
include: lake and pond dredging, lake aeration, and phosphorus inactivation (alum treatment).
Dredging the pond would be more economically feasible than dredging the lake, and should be a
priority. Hypolimnetic aeration is most applicable for the lake; the pond does not require aeration
due to its shallow nature. Continuous alum treatment is more applicable at Lake Carey than batch
alum treatment. All of these in-lake options would require feasibility studies to determine their
effectiveness.
In addition, a modified lake monitoring program should be continued in order to document any
improvements after implementing the lake and watershed management plan. A baseline
macrophyte survey should be performed to document the macrophyte distribution in the lake and
to detect any invasive species. Annual macrophyte surveys should follow.
8.4
Implementation Schedule
In-lake management alternatives such as phosphorus inactivation and hypolimnetic aeration are
important management techniques for Lake Carey, but should not be used in lieu of watershed
management practices. Until specific identified problems within the watershed are addressed,
nutrients and sediments will continue to enter the lake system and water quality will be
negatively impacted. In-lake alternatives should only be implemented after some or all of the
watershed management recommendations are implemented for greatest efficacy.
Implementation of the recommended management plan can be organized into short-term and
long-term action plans, as follows:
Short-Term Action Plan
The short-term action plan should consist of the following:
1.
Submit Growing Greener Application to:

Control Existing Stormwater Problem Areas

Expand Public Education Program

Develop Municipal Ordinances
2.
Implement Expanded Public Education Program
3.
Perform 537 Wastewater Management Plan Revision and Evaluate:

Decentralized Systems

Centralized Systems

Funding Sources
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
94
F. X. Browne, Inc.
4.
Encourage Easements and Develop or Revise Existing Ordinances:

Conservation Easements

Riparian Buffer Ordinance

Conservation Ordinance

Stormwater Management Ordinance

Zoning Ordinance
5.
Investigate the Feasibility of Dredging the Pond and/or Spot Dredging of
the Pond and Lake
6.
Evaluate Funding Opportunities

Growing Greener Program

Penn Vest

Special Appropriations
7.
Continue Modified Water Quality Monitoring Program
Long-Term Action Plan
The long-term action plan is designed to be performed after progress has been made on reducing
the sediment and nutrient loadings from failing septic systems and watershed erosion and runoff.
Some elements of the long-term action plan could be performed concurrently with the short-term
action plan. The long-term action plan consists of the following:
1.
Investigate the Feasibility of Installing a Hypolimnetic Aeration System in
the Lake.
2.
Investigate the Feasibility of Adding Alum to Meade Brook to reduce the
phosphorus load to Lake Carey.
3.
Implement Dredging of Pond and/or Lake Based on Feasibility Study
8.5
Funding Sources
The two primary funding sources for implementing the recommended management plan are the
Pennsylvania Department of Environmental Protection (PA DEP) Growing Greener Program and
the EPA's 319 Nonpoint Source Program. The Growing Greener Program provides funding to
perform watershed protection programs, implement best management practices, and develop
public education programs. The 319 Nonpoint Source program is administered in Pennsylvania
through the Growing Greener Program, and provides funds for watershed management projects
and public education programs.
Another funding source is the Conservation Reserve Enhancement Program (CREP) which helps
to support the installation of conservation practices on farms through the Pennsylvania
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
95
F. X. Browne, Inc.
Association of Conservation Districts (PACD). CREP is a federal program in which the U.S.
Department of Agriculture (USDA) partners with states to reduce sediment or nutrient runoff
from agricultural land. The USDA provides 50 percent of the funds necessary to install
conservation measures, such as filter strips, permanent vegetative cover or riparian buffers.
Additional funds come from the Growing Greener program. Farmers in the Lake Carey
watershed should be encouraged to apply for funding under the CREP program to implement
BMPs on their land.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
96
F. X. Browne, Inc.
9.0
References
Carlson, R. E. 1977. A trophic state index for lakes. Limnol. Oceanogr. 22:361-369.
Chapra, S. C. 1975. Comment on ‘An Emperical Method of Estimating the Retention of
Phosphorus in Lakes,’ by W.B. Kirchner and P.J. Dillon. Water Resources Res. 2(6):1033-1034.
Cooke, G. Dennis, Eugene B. Welch, Spencer A. Peterson, Peter R. Newroth. 1993. Restoration
and Management of Lakes and Reservoirs, Second Edition. Lewis Publishers, Boca Raton, FL.
Harper, H.H., J.L. Herr, and E.H. Livingston. 1998. Alum Treatment of Stormwater Runoff – An
Innovative BMP for Urban Runoff Problems. pp. 205-211.
Jones, C.W. and J. Taggart. 2001. Managing Lakes and Reservoirs. North American Lake
Management Society and Terrene Institute in Cooperation with the Office of Water, Assessment
and Watershed Protection Division, US EPA, Madison, WI.
Jones, J. R., and R. W. Bachmann. 1976. Prediction of Phosphorus and Chlorophyll Levels in
Lakes. J. Water Poll. Control Fed. 48(9):2176-2182.
Kirchner, W. B., and P. J. Dillon. 1975. An Emperical Method of Estimating the Retention of
Phosphorus in Lakes. Water Resources Res. 11(1)182-183.
Larsen, D. P., and H. T. Mercier. 1976. Phosphorus Retention Capacity of Lakes. J. Fish.Res.
Bd. Cann. 33(8):1742-1750.
Novotny, Vladimer, Ph.D., P.E., and Gordon Chesters, Ph.D., D.Sc., 1981,Handbook of
Nonpoint Pollution Sources and Management, Van Nonstrand Reinhold Company, New York,
NY.
Olem, H. and G. Flock, eds. 1990. Lake and Reservoir Restoration Guidance Manual. 2nd
edition. EPA 440/4-90-006. Prep. by N. Am. Lake Manage. Soc. for U.S. Environ. Prot. Agency,
Washington, D.C.
Pennsylvania Department of Environmental Protection, 2003. Watershed Notebook for Subbasin
01B, Lackawaxen River, Harrisburg, PA.
Pennsylvania Department of Environmental Protection, 1999. Document I.D.: 391-2000-010,
Implementation Guidance for Section 95.6 Management of Point Source Phosphorus Discharges
to Lakes, Ponds, and Impoundments, Harrisburg, PA.
Prairie, Y.T. 1989. Statistical Models for the Estimation of Net Phosphorus Sedimentation in
Lakes. Journal Info Aquatic Sciences. v 51 n 3192.
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
97
F. X. Browne, Inc.
Reckhow, K. H., and M. N. Beaulac, and J. T. Simpson. 1980. Modeling phosphorus loading and
lake response under uncertainty: A manual and compilation of export coefficients. Report No.
EPA-440/5-80-011.
Reckhow, K. H. 1977. Phosphorus Models for Lake Management. Ph.D. dissertation, Harvard
University.
Schueler, T. R. 1987. Controlling Urban Runoff: A Practical Manual for Planning and Designing
Urban BMPs. Prepared for: Washington Metropolitan Water Resources Planning Board.
Sunday Wilkes-Barre Times Leader. Lake Carey’s Almost Names, Retrieved from
www.advsolutions.com/carey/lakecarey.htm.
Susquehanna River Basin Commission, March 2, 2001. Total Maximum Daily Loads (TMDLs)
Lake Carey, Wyoming County.
Ulanoski, J. T., R. H. Shertzer, J. L. Barker, and R. T. Harman, 1981. Trophic Classification and
Characteristics of Twenty-Six Publicly Owned Pennsylvania Lakes. Bureau of Water Quality
Management, Pennsylvania Department of Environmental Resources, Publication No. 61, 240
pages.
United States Census Bureau, 2002. 2000 Census for Municipalities in Wayne County, PA.
Retrieved from http://www.census.gov/main/www/cen2000.html.
United States Department of Agriculture, Soil Conservation Service, 1985, Soil Survey of
Wayne County, Pennsylvania, Washington, D.C.
U.S. Environmental Protection Agency, “Clean Lakes Program Guidance Manual,” EPA-440/581-003, Washington, D.C. (1980).
Vollenweider, R. A. 1969. Possibilities and Limits of Elementary Models Concerning the Budget
of Substances in Lakes. Arch. Hydrobiol. 66(1):1-36.
Walker, W. W., Jr. 1977. Some Analytical Method Applied to Lake Water Quality Problems.
PhD. dissertation, Harvard University.
Wetzel, R. G. 1975. Limnology. W.B. Saunders Company. Philadelphia.
Wyoming County Historical Society, Lake Carey Facts. Retrieved from
www.scrantontimestribute.com/stories/Tornado/27260.htm
NCDC National Climatic Data Center, 2004. Wilkes Barre Scranton W, Luzurne County (NCDC
9705).
Lake Carey Watershed Assessment and Watershed Management Plan
October 2004
PA1590-01-001
98
Appendix A
Glossary of Lake and Watershed Management Terms
Appendix B
Dissolved Oxygen and Temperature Profile Data
Appendix C
Water Quality Data
Appendix D
Phytoplankton Data
Appendix E
Zooplankton Data
Appendix F
Sediment Testing Data
Appendix G
Stream Water Quality Data
Appendix H
Jar Testing Data
]
Appendix I
Well Water Quality Data