Chicago April 24, 2003 16th Annual National Conference Concord, Massachusetts wwwalker.net Enhancing the States' Lake Management Programs Experience in Developing Phosphorus TMDLs for Lakes William W. Walker, Jr., Ph.D. Environmental Engineer - Conceptual Model - Deriving TMDL Goals - Phosphorus Mass-Balance Models - Available Software - Examples Phosphorus TMDL's for Lakes Topics
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Experience in Developing Phosphorus TMDLs for LakesLake Inputs Nutrients Algal Growth Water Quality Water Uses Algal Blooms Transparency Aesthetics DO Depletion Recreation ... Conceptual
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Chicago
April 24, 2003
16th Annual National Conference
Concord, Massachusettswwwalker.net
Enhancing the States' Lake Management Programs
Experience in Developing Phosphorus TMDLs for Lakes
William W. Walker, Jr., Ph.D.Environmental Engineer
- Conceptual Model
- Deriving TMDL Goals
- Phosphorus Mass-Balance Models
- Available Software
- Examples
Phosphorus TMDL's for LakesTopics
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Lake Inputs Nutrients Algal Growth Water Quality Water Uses
Algal Blooms
Transparency Aesthetics
DO Depletion Recreation
pH Fisheries
Ammonia Water Supply
Turbidity
Sediments Taste & Odor
Toxic Organics
Other Controlling Factors
Causal Pathways Linking P Loads to Water Uses
Watershed P Load
Lake Mean Phosphorus
Mean Chlorophyll-a
Lake Inputs Nutrients Algal Growth Water Quality Water Uses
Based upon Log-Normal Frequency Distribution Models Calibrated to Various DatasetsWalker, W., "Statistical Bases for Mean Chlorophyll-a Criteria", Lake & Reservoir Mgt, 1985
Statistical Basis for Mean Chlorophyll-a CriteriaFrequency of Severe Nuisance Blooms vs. Mean Chl-a
0%
10%
20%
30%
40%
50%
60%
0 10 20 30 40
Mean Chlorophyll-a (mg/m3)
Perc
ent >
30
Vermont LakesCE ReservoirsSA Reservoirs
“Threshold”
4
Algal Bloom Frequency vs. Total PhosphorusSt. Paul Water Supply
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
0 10 20 30 40 50 60 70Lake Total P (ppb)
Freq
. Chl
-a >
30
ppb
PleasantVadnaisPredicted
Goal = 25 ppb
Algal Bloom Frequencies vs. Mean Chl-a in Different YearsHeiskary & Walker, "Establishing a Chlorophyll-a Goal for a Run-of-the River Reservoir"Lake & Reservoir Management, 1995
Development of a Chlorophyll-a Goalfor Lake Pepin, Minnesota
> 40 ppb
> 60 ppb
GoalMean < 30 ppb
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Algal Bloom Frequencies vs. Mean Chl-aOnondaga Lake, New York
Near-Shore Bloom Frequencies vs. Pelagic Mean TPLake Okeechobee, Florida
0
10
20
30
40
50
0 20 40 60 80 100 120
Yearly Mean TP (ppb)
Blo
om F
requ
ency
( %
)
Chl-a > 40 ppb
Chl-a > 60 ppb
Lake P Target40 ppb
Havens & Walker, Lake & Reservoir Mgt, 2002
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Total P Standard Based upon TransparencyPlatte Lake, Michigan
StandardMean TP = 8 ppb
Y-Axis = Frequency of Secchi Depths < 10 feet
Freq. Secchi < 4 ft vs. Predicted TPOnondaga Lake, New York
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Derivation of P Target for Compliance with pH StandardUpper Klamath Lake, Oregon
Data from Marsh Transects along P Gradient in Water Cons. Area 2AImpact = Significant Change from Reference SitesSouth Florida Water Mgt Dist. & Florida Dept of Env. Protection, 2002
Derivation of TP Criterion for Everglades MarshPercent of Biological Indicators Impacted vs. Mean TP
DO, Macroinvert., Periphyton, Algal Mats, Open Water, Macrophytes
Observed & Predicted Values - Upper Klamath Lake Model
050
100150200250300350400450500
1991 1992 1993 1994 1995 1996 1997 1998 1999
Tota
l P (p
pb)
LakeOutflowCalibration
Calibration Period ------------>
050
100150200250300350400450
1991 1992 1993 1994 1995 1996 1997 1998 1999
Chl
orop
hyll-
a (p
pb)
7.0
7.5
8.0
8.5
9.0
9.5
10.0
10.5
1991 1992 1993 1994 1995 1996 1997 1998 1999
pH
Water Quality Standard
pH Violation Frequency vs. Average Inflow P ConcentrationUpper Klamath Lake
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Evaluation of Phosphorus Standards for Cherry Creek Reservoir
presentation before Colorado Water Quality Commission
William W. Walker, Jr. , Ph. D. Environmental Engineer
September 11 , 2000
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Y Axis: Percent of Days in July - September with Chl-a Exceeding 10, 20, or 30 ppb
Cherry Creek Reservoir, ColoradoAlgal Bloom Frequencies vs. Mean Chlorophyll-a
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0 5 10 15 20 25 30July-Sept. Mean Chlorophyll-a (ppb)
Alg
al B
loom
Fre
quen
cyAlgae Visible> 10 ppb
NuisanceBloom
> 20 ppb
Severe Nuisance> 30 ppb
"Goal"Mean Chl-a < 15 ppb
Summer Mean Chl-aStandard Error ~ 34%
Linkage of Models Used to ForecastCherry Creek Reservoir Chlorophyll-a Levels
P Balance Model
Watershed Model
Management Scenario
Uncertainty
Chla- Model
Climate
Reservoir Total P
Reservoir Chl-a
Runoff & P Load
Depth & Area
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Risk Frequency of Years with July-Sept Mean Chl-a > 15 ppbMean Average Risk or Frequency over 10 Years (1989-1998)Max Risk in Highest Runoff Year (1998)
Risk of Exceeding 15 ppb Mean Chl-a vs.Alternative Total P Standards
Based upon Simulation of 1989-1998 Hydrologic Record