Mecklenburg County Water Quality Program
1.
2.
3.
4.
Waters of Mecklenburg
Program Purpose
Program Activities
Watershed Management
¾
¾
¾
¾
Watershed Ranking/Prioritization
Plan Development
Cost Benefit Analyses
Implementation
5. The “Big Picture”
Mountain Island Lake ends where Lake Wylie begins.
RSR1
Waters of Mecklenburg
Davidson
Cornelius
Huntersville
Charlotte
Mint Hill
Matthews
Pineville
Our Most Precious Natural Resource
Slide 2
RSR1
CMU on Lake Norman = 25 mgd for northern Towns
CMU on MIL = 85 mgd for Charlotte and southern Towns
Mount Holly on MIL = 2 mgd for 12,671 population
Gastonia on MIL = 16 mgd for 110,000 population
Belmont on Lake Wylie = 2 mgd for 8,700 population
Rock Hill on Lake Wylie = 7 mgd for 57,000 population
Total = 144 mgd for 1,000,000 population from 6 intakes in 3 counties
rozzers, 2/18/2008
We’re All Downstream!
Cabarrus
N.C.
S.C.
York
Union
Recreational Uses
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Over 10 million people visit
the Catawba River annually.
Visitation is projected to
increase by about 11
percent per decade through
2050.
The Mecklenburg County
greenway system is quickly
becoming one of the finest in
the country.
There are 33 miles of
developed and 147 miles of
undeveloped greenways in the
County.
Other Lake Uses
„
50 percent of Duke Power’s
capacity for electric generation
relies on the Catawba River.
„
This includes hydro power at
the dams and cooling water at
the nuclear and coal fired
plants.
„
Latta Plantation Nature Preserve
is located on 1,343 acres along
Mountain Island Lake.
This area preserves the habitat
for 137 species of birds,
mammals, reptiles, and
amphibians as well as 2 federally
endangered species of plants.
„
Economic Boom Around the Lakes
Maintaining good water
quality conditions in our
streams and lakes is
essential for maintaining
a livable community.
Ladies fishing in Little Sugar Creek – circa 1890
Swimming hole in Long Creek – circa 1910
Kids wading in Little Sugar Creek – circa 2000
Over the past 20 years in CharlotteMecklenburg:
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Population has increased by 81%.
Developed areas have tripled.
Naturally vegetated areas have decreased by 70%.
Storm water pollution sources have increased by 55%.
Water use has doubled.
Increased threat to water quality meets an increased
demand for clean water.
er
y Riv
Rock
Impaired Streams in
Mecklenburg County
(303(d)) List)
k
ee
Cr
l
l
we
Do
Mc
Catawba
reek
ks C
Clar
Yadkin River Basin
Yadkin
Catawba River Basin
McKe
e Cre
ek
k
ee
Cr
Irw
in
Cre
ek
ng
Lo
Goose Creek
k
ee
Cr
e
in
lp
cA
M
Litt
le S
uga
r Cr
eek
Sugar Creek
k
ree
ar C
e
l
C
Catawba Basin
Yadkin Basin
Irwin Creek
McKee Creek
Stewart Creek
Rocky River
Taggart Creek
Clarks Creek
Coffey Creek
Crooked Creek
Kings Branch
Clear Creek
Sugar Creek
Goose Creek
Briar Creek
Little Sugar Creek
McMullen Creek
Four Mile Creek
N Fork Crooked Creek
McAlpine Creek
Long Creek
McDowell Creek
Legend
Charlotte
Cornelius
Davidson
Huntersville
Matthews
Mint Hill
Pineville
Streams Listed on NC 303(d) list
River Basin Drainage Divide
Four Mile Creek
N
2
0
2
4 Miles
McCullough Branch
The goal of the Water Quality Program
is to protect and restore the quality and
usability of Mecklenburg County’s
surface water resources.
Goose Creek in Mint Hill
Water Quality Program Activities
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
Respond to pollution problems and concerns (citizen requests).
Monitor water quality conditions.
Inspect and monitor municipal facilities, businesses, and industries.
Respond to spills and other emergency situations.
Survey streams and lake shoreline.
Implement Phase I and Phase II Storm Water Permit requirements.
Conduct educational activities and volunteer programs.
Enforce pollution control regulations.
Develop and implement TMDLs for 303(d) listed streams.
Enforce post-construction ordinance requirements.
Enforce sedimentation and erosion control ordinance requirements.
Perform water quality modeling and watershed planning.
Briar Creek in Charlotte
Modeling & Watershed Planning
Goal: Protect and restore water quality conditions through
the development and implementation of watershed
management plans.
Surface Water Improvement & Management (S.W.I.M.):
Activities are performed in support of the County’s S.W.I.M.
Policy which states: “Surface water resources in
Mecklenburg County shall be supportive of varied species of
aquatic life and suitable for human contact.”
Capital Improvement Program (CIP): Implemented as a
component of our CIP (with matching funds sought from a
variety of State and Federal grants.
McDowell Creek and Cove
Step 1: Watershed Ranking/Prioritization
ROCKY RIVER
WEST BRANCH
LAKE
NORMAN
CLARKE
UPPER MTN
ISLAND LAKE
TORRENCE
CREEK
„
County was segmented into 39
watersheds/assessment units.
„
Each assessment unit was
evaluated for factors indicative of
watershed health, anticipated
changes in the watershed and
ability to construct projects.
„
The fundamental philosophy
behind the process is to focus on
areas needing restoration not on
areas needing preservation.
„
14 criterion were selected and
grouped into two broad
categories, including Existing
Conditions Criteria and
Management Criteria.
„
Updated every 2 years.
LOWER
CLARKE
MC DOWELL
GAR
LOWER MTN
ISLAND/
UPPER WYLIE
MALLARD
LONG CREEK
UPPER
IRWIN
BACK
STEWART
PAW CREEK
REEDY
TAGGART
LAKE
WYLIE
BRIAR
KINGSLOWER
LITTLE
SUGAR
STEELE
CAMPBELL
UPPER
MC ALPINE
UPPER
LITTLE
SUGAR
COFFEY
CALDWELL
MC KEE
MCMULLEN
SUGAR
IRVINS
MID MC ALPINE
CLEAR
GOOSE
CROOKED
FOUR MILE
LOWER
MC ALPINE
CLEM
TWELVE
MILE
SIX MILE
Watershed Ranking/Prioritization
Watershed Ranking Criteria
Management Conditions
Existing Conditions
Endangered Species
SUSI Scores
Water Supply Watershed
Stream Erosion Index
Watershed Planning
Presence of Forested Buffers
Effectiveness of LD Ordinances
Existing Impervious Area
TMDL and 303(d) Listing
Habitat
Future Development
Publicly Owned Parcels
Services Requests
Project Feasibility
Lake Norman
Management Conditions Criteria
Purpose: Assess existing ordinances, NPDES permit
requirements, planning and other “management related”
factors affecting future conditions in each watershed.
• Endangered Species
• Water Supply Watershed
• Watershed Planning
• Effectiveness of LD Ordinances
• TMDL and 303(d) Listing
Lake Wylie
Endangered Species
Purpose: Focus efforts in areas with endangered or
threatened species and areas identified for re-colonization.
3 pts for endangered
species
„ 2 pts for
threatened/special
concern species
„ 1 pt for re-colonization
area
„ 0 pts for no known
issues
„
Carolina Darter (Threatened)
Carolina Heelsplitter (Endangered)
Water Supply Watershed Designation
Purpose: Focus efforts in areas draining
directly to drinking water supply reservoirs.
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3 pts for watersheds draining to Mountain Island Lake
2 pts for watersheds draining to Lake Norman
1 pt for watersheds draining to Lake Wylie
0 pts for watersheds not draining directly to water supply.
Watershed Planning
Purpose: Focus
efforts in areas with
existing watershed
plans (temporary).
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McDowell Creek Watershed
3 pts for completed
plan
2 pts for plan under
development
1 pts for scheduled
production of plan
0 pts for no scheduled
watershed plan
Effective Land Development Regulations
Purpose: Focus efforts in areas with effective land
development ordinances (effects longevity of projects).
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„
Town of Huntersville
3 pts for
Huntersville and
Mint Hill Goose
Creek
2 pts for Davidson,
Matthews and
Charlotte
1 pt for Cornelius,
Mint Hill other than
Goose, Pineville and
Mecklenburg
TMDL and 303(d) Listing
er
y Riv
Rock
k
ee
Cr
l
l
we
Do
Mc
reek
ks C
Clar
Yadkin River Basin
Catawba River Basin
k
ee
Cr
McKe
e Cre
ek
„
Irw
in
Cre
ek
ng
Lo
Purpose: Focus efforts in areas
identified on 303(d) list as not
meeting designated uses.
ek
re
eC
n
i
lp
cA
M
Goose Creek
Sug
ar C
ree
k
Litt
le
Sugar Creek
k
ree
ar C
Cle
N Fork Crooked Creek
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Legend
Charlotte
Cornelius
Davidson
Huntersville
Matthews
Mint Hill
Pineville
Streams Listed on NC 303(d) list
N
3 pts for completed
TMDL and Water
Quality Recovery
Program
2 pts for completed
TMDL
1 pt for 303(d) listing
0 pts for unlisted
watersheds
Future Development
Purpose: Focus efforts in “Built Out” watersheds with the least
expected future degradation from land development activities –
calculated from difference between existing and build out
impervious levels.
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3 pts for <10%
Increase in
impervious
2 pts for 10-15 %
Increase
1 pt for 15 – 20%
Increase
0 pts for >20%
Increase
Management Conditions Criteria
Endangered Species, Water Supply Watershed, Watershed Planning, Effectiveness of LD
Ordinances, TMDL/303(d) Listing, and Future Development
Name
Score
GOOSE
2.2
TORRENCE CREEK
1.8
MC DOWELL
1.8
GAR CREEK
1.3
IRVINS CREEK
1.2
ROCKY RIVER WEST
BRANCH
1
CLARKE CREEK
1
SIX MILE CREEK
1
STEELE
1
CROOKED
0.8
Existing Conditions Criteria
Purpose: Focus efforts in areas that have the highest
current level of degradation.
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SUSI Scores
Stream Erosion Index
Presence of Forested buffers
Existing Impervious Area
Aquatic Habitat
Publicly Owned Parcels
Storm Water Service Requests
Project Feasibility
Sewage in Creek
Stream Use Stream Index (SUSI)
Purpose: Focus efforts in areas with poor water quality.
S
#
MY1B
SUSI Jun-08
Supporting
Partially Supporting
Impaired
Degraded
No Data
MY10
S
#
MC4
S
#
MC50
S
#
MY11B
S
#
MY12
MC14A
S
#
S
#
MY13
S MY7B
#
S
#
MC17
S
#
MY8
S
#
MC29A1
S
#
MC22A
S
#
MC33
S
#
MC25
S
#
MC42
S
#
MC47A
S
#
MC27
S MC49A
#
S
#
MC40A
S
#
MC45
S
#
MC51
Based on:
S
#
MC38
S
#
MY9
S
#
3 pts for impaired
„ 2 pts for threatened
„ 1 pt for partially
supporting
„ 0 pts for supporting
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Stream Erosion Index
Purpose: Focus efforts in “at risk” streams
under existing conditions
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3 pts for streams with >20% at risk
2 pts for streams with 10-20% at risk
1 pt for streams with 6-10% at risk
0 pts for streams with 0-5% at risk
Eroded Channel
Forested Buffers
Purpose: Focus efforts in areas with impacted buffers.
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3 pts for buffers
with <60% forest
2 pts for buffers
with 60-80% forest
1 pt for buffers with
80-90% forest
0 pts for buffers
with >90% forest
Existing Impervious Percentage
Purpose: Focus efforts in areas with higher
percentages of existing impervious cover.
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3 pts for levels
>25%
2 pts for levels 12
– 25%
1 pt for levels 6 –
12%
0 pts for levels
<6%
Aquatic Habitat Change from 2000 – 2005
Purpose: Focus efforts in areas with degrading
aquatic habitats scores.
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3 pts for decrease in scores >50 pts
2 pts for decrease in scores between 25 and 50 points
1 pt for decrease in scores between 0 and 25 points
0 pts for an increase in scores (improving habitat)
Rocky Branch, Charlotte
Existing and Expected Public Lands
Purpose: Focus efforts in areas with a greater percentage
of public ownership – easier to get projects in the ground.
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3 pts for >15% Public
2 pts for 10-15% Public
1 pt for 5 – 10% Public
0 pts for <5% Public
Service Requests
Purpose: Focus efforts in areas with more service
requests regarding channel degradation.
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3 pts for >5 SRs
2 pts for 3 or 4 SRs
1 pt for 1 or 2 SRs
0 pts for 0 SRs
Project Feasibility
Purpose: Focus efforts in areas with fewer property owners to
improve likelihood of obtaining easements (based on metric
calculated by dividing # of stream miles by the # of parcels).
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Bad
Good
3 pts for >450
2 pts for <450
and >250
1 pt for <250 and
>100
0 pts for <100
Existing Conditions Criteria
SUSI, Stream Erosion, Buffers, Existing Impervious, MHAP, Public Parcels, Service
Requests, and Project Feasibility
Rank
Name
UPPER IRWIN CREEK
1
UPPER LITTLE SUGAR
CREEK
2
LOWER LITTLE SUGAR
CREEK
3
IRVINS CREEK
4
BRIAR CREEK
5
UPPER MC ALPINE
CREEK
6
LOWER MC ALPINE
CREEK
7
STEWART CREEK
8
SUGAR CREEK
9
FOUR MILE CREEK
10
Management & Existing Conditions
Criteria Combined
Name
Score
Rank
MC DOWELL
1.8
1
GOOSE
1.8
2
TORRENCE
1.7
3
UPPER LITTLE SUGAR
1.7
4
IRVINS CREEK
1.6
5
UPPER IRWIN CREEK
1.5
6
LOWER LITTLE SUGAR
1.5
7
BRIAR CREEK
1.5
8
UPPER MC ALPINE
1.5
9
LOWER MC ALPINE
1.5
10
Step 2: Watershed Management Plan
Development
Restoring Water Quality
in McDowell Creek
McDowell Creek at Mountain Island Lake in Huntersville
McDowell Creek Watershed
McDowell Creek Watershed
Background
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McDowell Creek drains portions of the Towns of
Huntersville and Cornelius.
The water quality in McDowell Creek Cove is some
of the poorest in the Catawba River and is
currently impaired with sediment as the primary
pollutant.
A modeling effort undertaken in 2002 predicted
pollutant loads to triple as the watershed builds
out.
McDowell Creek is upstream of our drinking water
intake.
Linearized Portion of McDowell Creek
The Approach
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Mecklenburg County elected to take action to
restore McDowell Creek as part of its S.W.I.M.
Initiative & CIP.
The County worked in cooperation with the
Towns to develop and implement effective
ordinances to prevent increased pollution.
A Watershed Management Plan was developed
and is being implemented to reduce existing
sources of pollution.
Management Plan Structure
The Plan focuses on 3 sources of water quality
impairment:
„ Upland
Sources – Runoff from existing
development
„ In-Stream Sources – In-stream erosion
caused by increased storm water volume and
velocity
„ Stream Corridor – Ineffective stream buffers
Overall Results
Upland Sources
Resulted in Focus Areas
Upland assessment completed using
monitoring and modeling data.
„ TSS used as indicator/surrogate.
„ Watershed divided into catchments
scored on the amount of pollution
produced.
„
The
Ugly
The
TheAssessment
Good
Bad
In-Stream
Channel impairment was identified
through extensive field investigations.
„ Accumulative scores were assigned to
impaired channel sections (from 0-20
assigned).
„
The
TheCorridor
Good
Bad
Stream
„
„
„
Utilized remotely sensed American Forest’s
Tree Canopy data set.
Intersected data set with FEMA floodplain and
local buffers.
Un-forested buffers were identified for reforestation.
‰ Public parcels (such as parks) are the low
hanging fruit.
Step 3: Cost-Benefit Analysis
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Watershed goal was set at 0.3 tons of sediment
/acre/year.
The results of the upland and in-stream assessments
were compared and a cost analysis performed.
90% of the sediment is from in-stream sources.
Cost to remove in-stream sources is many times less
than removing upland sources.
Conclusion: Restoring the stream channel is the
key to restoring water quality in McDowell Creek!
Cost-Benefit Analysis
The relative contribution of sediment to McDowell Creek was
estimated through an evaluation of the stream assessment data
30000.0
and
the calculated upland load (presented in the McDowell Creek
Watershed Management Plan). The following table presents the
25000.0
estimated annual sediment production by category.
Sediment (tons/year)
35000.0
20000.0
System
Total Length
(miles)
Major Stream System
30.4
15000.0
10000.0
Minor Stream System
5000.0
0.0
Upland
93.0
NA
Total
Major System
Estimated Annual
Sediment Load
(tons)
Percent
Breakdown
14,568.7
29%
30,060.0
59%
6,162.61
12%
50791.3
Minor System
100%
Upland
Cost-Benefit Analysis
If the goal is multiplied by the area of the watershed (18,283
acres) it can be expressed as an overall annual load of 5,485
tons.
Existing TSS Load in tons/year (from above)
50,791
In-Stream TSS Goal (0.3 tons/acre/year) expressed in tons/year
5,485
Load Reduction Required (tons)
45,306
Load Reduction Required in percent
89%
Cost-Benefit Analysis
A detailed cost analysis comparing BMP installation, minor
system stream enhancement and major system stream
enhancement was prepared. A cost of $300 per linear foot (LF)
for stream restoration was used to estimate the overall stream
restoration project cost.
System
Assessed
Length
(feet)
Assessed
Sediment
Load (tons)
Assessed
Sediment
Load
(tons/LF)
Cost of
Stream
Restoration
/LF
Cost per
pound of
sediment
removed
Major
62811.6
5,704.8
0.0908
$300
$1.65
Minor
93083.5
8,458.0
0.0909
$300
$1.65
Cost-Benefit Analysis
TSS removal efficiencies and sediment loading per acre of
land-use values were obtained from the Post Construction
Ordinance Process. The results of the analysis are as follows:
.
BMP Type
Cost/ac Treated
TSS Removal
Efficiency
Average $/lb
TSS removed
Sand Filter
$20,000
85%
$24.43
Wet Pond
$22,000
65%
$35.15
Wetland
$31,500
65%
$50.33
Rain Garden
$16,000
85%
$19.55
Extended Detention
$31,500
47%
$69.60
WQ Swale
$3,000
80%
$3.89
Filter Strip
$3,000
50%
$6.23
Pond Retrofit
$6,700
35%
$19.88
Cost-Benefit Analysis
„
„
It is 2 times cheaper to remove a pound of
sediment through stream restoration than
from the most cost effective BMP (WQ
Swale).
BMPs will continue to play a role in
attenuating temperature and removing
hydrocarbons from built upon areas.
Step 4: Implementation
1. Conduct stream restoration and enhancement in the major
and minor systems (main focus).
2. Retrofit currently untreated concentrations of impervious
cover with BMPs designed to reduce temperature and toxic
pollutants.
3. Reforest buffers as needed to attenuate temperature spikes
through providing additional shade for the stream corridor.
4. Design stream restoration and enhancements to focus upon
improving habitat in addition to limiting sediment load.
5. When possible and cost effective, retrofit existing ponds to
provide additional TSS removal and, if possible,
temperature attenuation.
Implementation
RANK (NEED
&
FEASIBILITY)
REAC
H
RECOMMENDATI
ON
FEASIBILITY
ASSESSED
LENGTH
(ft)
RANK
(NEED)
BASIN
Sediment Load
Removed
(tons/year)
Approximate
Cost
1
B1a
Enhancement I
Minimal
433
5
B
54.7
$64,950
2
P14b
Restoration
Minimal
2,137
7
P
2.73
$641,100
3
I4a_I5a
Restoration
Minimal
1,132
8
I
115.7
$339,600
4
O47a
Restoration
Minimal
7,395
9
O
371.1
$2,218,500
5
P14a
Restoration
Minimal
1,663
11
P
97.73
$498,900
6
I7a
Restoration
Minimal
680
12
I
53.9
$204,000
7
K7a
Restoration
Moderate
2,795
2
K
240.07
$838,500
8
M3c
Enhancement II
Minimal
1,710
18
M
110.7
$85,500
9
O44
Enhancement II
Minimal
1,228
19
O
55.1
$61,400
10
K7d
Restoration
Moderate
1,171
3
K
100.7
$351,300
Implementation
Grant
Grant
Source
Amount
Clean Water $984,000
Management
Match
Amount
$984,000
Total
$1,968,000
319
$668,711
$414,772
$1,083,483
NCNRC
$95,000
$105,000
$200,000
Totals
$1,747,711
$1,503772
$3,251,483
Implementation
Capital Improvement Project
Northcross Shopping Center, Huntersville
$1,600,000 in State and federal grants
Goal: Reduce the pollutant load in
McDowell Creek by 36% by 2020 and
restore aquatic life.
Continuous Monitoring and Alert Notification
Network (CMANN)
The “Big Picture”
Hidden Valley Project in Charlotte
Before
During
After
Combination of Flood Mitigation with
Water Quality Restoration
Questions?
Catawba River Valley