ASSIMILATIVE CAPACITY WATER QUALITY
MODELING AND
WATER QUALITY STANDARDS REVIEW
Contract in Support of the Georgia
Comprehensive State-wide Water
Management Plan (GA State Water Plan)
Presented by:
Brian J. Watson, PE, PH
25 May 2011
Oregon Water Conference 2011
Corvallis, Oregon
“The purpose of this plan, as
stated by O.C.G.A. §12-5522(a), is to guide Georgia in
managing water resources in
a sustainable manner to
support the state’s economy,
to protect public health and
natural systems, and to
enhance the quality of life for
all citizens”
Georgia State-Wide Water Plan

Governor developed a Water
Council to address water
management issues:
•

Water Council is made up of
11 planning regions
•


Drought, Corps, water supply,
wastewater capacity, growth
Political Boundaries not
watershed boundaries
$36.5M to develop the tools
and plans for all regions
($20M contracted out)
Resource Assessments
•
•
•
Assimilative Capacity
Surface Water Availability
Groundwater
http://www.georgiawaterplanning.org
TN
NC
Carters
Lake
Legend
Lake Sidney
Lanier
DOSag Model
RIV1 Model
Lake
Hartwell
GA Estuary Model
Watershed Model
SC
Lake/Estuary Model
Lake
Weiss
C
tta
ha
h
ch
oo
ee
R
iv
Lake
Jackson
Allatoona
Lake
er
J. Strom
Thurmond
Lake
Major Waterway
Water Planning Region
County Boundary
Lake
Lake
Oconee
Savannah
River
Lake
Sinclair
i
ee R
ver
ee
ulg
er
Riv
ah
a
 Lake
Sinclair
Brunswick
River Watershed
Ri
v
er
 Lake
SatillaCheehaw/Worth
River Watershed
tR
iv
er
 Upper
Apalachee
Savannah
River Watershed
River Lakes
Fl
in
r
Riv
e
a
ico
l
ach
Ap
al
Lake
Walter
F. George
 Lake
Allatoona
Watershed
 Lower
Flint
River
Cathead
Creek
Estuary
 Lake
Oconee
Lower
Savannah
River Watershed
that have
point source
discharges
Al
ta
m
Lake
Seminole
Satilla
River
NAD_1983_UTM_Zone_17N
Map produced 02-03-2011 - P. Cada
West
Lake
CoosaPoint
River
WatershedRiver
 Lower
Chattahoochee
Satilla
Estuary
Lake
UpperJackson
Ocmulgee
Watershed
 Over
7,000
RiversRiver
and Streams
Brunswick
Harbor
Assimilative Capacity Models
Carters
 Lake
Lake
Lanier
Watershed
 Upper
Chattahoochee
River
Brunswick
Harbor
 Lake
UpperBlackshear
Oconee River Watershed
AND
Walter F.
George
Reservoir
Ochlocknee
River
Chattahoochee
Lake
Allatoona
River Watershed
 Coosa
River
Savannah
Harbor
Lake
 Carters
Seminole
Lake
Watershed
 Lower
Savannah
River
North
Newport
Estuary
n
Oco
m
Oc
Lake
Blackshear
Watershed
Lake
Estuary
River
Models
Models
Models
Models
Lake
Lanier
Flint
River
Watershed River
 Middle
Chattahoochee
St.
Marys
Estuary
AL
West
Point
Lake
Assimilative Capacity Models
FL
Suwannee
River
0
0
20
St.
Marys
River
40
20
80 Kilometers
40
80 Miles
St. Marys
 Tennessee
Lakes
Suwannee River Watershed
 St. Marys River Watershed
 Ohoopee River Watershed
 Tallapoosa River Watershed
Database and Models Used
 Database Management
• Water Resources Database (WRDB)
 Steady-State Models
• Georgia Dissolved Oxygen Sag (GaDosag)
• Georgia Estuary (GaEst)
 Watershed Model
• Loading Simulation Program C++ (LSPC)
 River Hydrodynamic and Water Quality Model
• EPD-Riv1
 Lake/Harbor Hydrodynamic and Water Quality
Model
• Environmental Fluid Dynamics Code (EFDC)
Model Linkage
Models
GaDosag
GaEst
Boundary
Conditions
Outputs
Dissolved Oxygen Sag Location
Permit Limits
(DO, BOD, NH3)
Point Source
Permit Limits
Subwatershed Flows
LSPC
Subwatershed Concentrations
(Chl-a, TN, NH3, NOx, OrgN, TP,
PO4, OrgP, BOD, DO, Temp, TSS, Fecal)
Flows
Temperatures
Concentrations
EPD-RIV1
EFDC
Downstream
Model
River – Flow
Lake/Harbor – Water Surface
River/Lakes – Temperatures
Harbor – Salinity
River/Lake/Harbor Concentrations
(Chl-a, TN, NH3, NOx, OrgN, TP,
PO4, OrgP, BOD, DO, Temp)
Types of Scenarios Being Evaluated
 Baseline (Calibrated)
 Baseline with PS/WD removed
 Current Permits
 All Forested/Natural
 2050 Full Build-out
 2050 with PS/WD removed
 Non-Point Source Management Practices
 U.S. Army Corp Operational Changes
 Total Maximum Daily Load (TMDLs)
 Waste Load Allocations (WLAs)
Sample Outputs for Scenarios
 Available Dissolved Oxygen
 GaDosag, GaEst, EPD-RIV1, EFDC
 Summarize by River Miles
 Spatial visualizations (GIS)
 Tributary Compliance Points
 TP/TN Loads
 Loading Rates (lbs/year)
 Point Source vs. Non-Point Source
 Lake Compliance Points
 Chlorophyll-a
 Phosphorus Loading (lbs/acre-ft/year)
 Total Nitrogen
 Watershed “Heat” Maps
Scale for Available Assimilative Capacity for
Dissolved Oxygen
< 0.0 mg/L of DO Available
None or exceeded capacity
0.0 mg/L of DO Available
At Assimilative Capacity
> 0.0 mg/L to < 0.2 mg/L of DO Available
Limited
0.2 mg/L to < 0.5 mg/L of DO Available
Moderate
0.5 mg/L to < 1.0 mg/L of DO Available
Good
≥ 1.0 mg/L of DO Available
Very Good
Available Dissolved Oxygen in
Upper Oconee Watershed
Baseline
2050
Conditions
Available Assimilative Capacity for
Dissolved Oxygen in River Miles
Baseline
Natural
Permitted
2050
“Good Miles”
5,410
6,016
4,773
5,517
%
76
84
67
77
“Bad Miles”
327
118
842
110
%
5
2
12
2
Available Dissolved Oxygen in Brunswick Harbor
Wet Year
Dry Year
Chlorophyll-a in Lake Jackson
Total Nitrogen in Lake Allatoona
Wet Year
Dry Year
Total Nitrogen
Lake Seminole
Lake Blackshear
Wet Year
Dry Year
Evaluation of Chlorophyll-a Targets
for West Point Lake
Modeling Complexities
AL GA
Lake Standards
Trib Standards
Corps Operation
Lake Lanier
Upper Chattahoochee
Lake Jackson
West Point Lake
Middle Chattahoochee
Lake Blackshear
Lake Walter F George
Lower Flint
Lower Chattahoochee
Lake Seminole
Modeling
Considerations
TMDLs
Nutrient Criteria Evaluation
Nutrient Criteria Development
Corp Operation Changes
WLAs
Florida Numeric
Nutrient Criteria
GA
FL
Supplemental Analysis and Reports
 Dissolved Oxygen Criteria
 Bacteria Criteria
 Significant Natural Resource Waters Use
Classification
 Uncertainty Analysis
 Agricultural Irrigation Implementation Report
 Weather File Development Report
 Naming Convention for Modeling Scenarios
 Numerous other Reports
Contacts
Brian J. Watson, PE, PH
Elizabeth Booth, PE, PhD
Tetra Tech
Watershed Planning and
Monitoring Program Manager
Director, Water Resources Group
2110 Powers Ferry Road
Suite 202
Atlanta, Georgia 30062
770-850-0949 x101
brian.watson@tetratech.com
Department of Natural Resources
Environmental Protection Division
Watershed Protection Branch
4220 International Parkway
Suite 101
Atlanta, Georgia 30354
404-675-1675
elizabeth.booth@dnr.state.ga.us
Questions?