SLIDE 1 Minnehaha Creek TMDL
Linkage Analysis Summary
April 12, 2012 Minnesota Pollution Control Agency Office g y
SLIDE 2 Minnehaha Creek TMDL
Approach Approach
Work Plan Elements
Watershed Characterization
Work Plan Elements
Source Assessment Linkage Analysis TMDL Implementation Plan TMDL
SLIDE 3 Minnehaha Creek TMDL
Linkage Analysis Linkage Analysis
Focus Focus
Connect the pieces
Hydrology
Provide technical basis to define TMDL components
SLIDE 4
Linkage Analysis
Discussion Overview Discussion Overview
Data Driven Approach Target Development Target Development Flow Estimates Flow Estimates Watershed Loading Allocation Options g
SLIDE 5 Linkage Analysis
Grays
Data Driven Approach Data Driven Approach
Grays Bay Lake Hiawatha West 34th Excelsior McGinty 32nd Ave Browndale Upton Chicago
McGinty
SLIDE 6
Minnehaha Creek
Longitudinal Profile Longitudinal Profile
Bacteria Bacteria
SLIDE 7
Minnehaha Creek
Longitudinal Profile Longitudinal Profile
Total Phosphorus Total Phosphorus
SLIDE 8
Lake Hiawatha
Chlorophyll-a (Response)
Seasonal Average Patterns Seasonal Average Patterns
Chlorophyll a (Response)
SLIDE 9
Lake Hiawatha
Secchi Depth (Response)
Seasonal Average Patterns Seasonal Average Patterns
Secchi Depth (Response)
SLIDE 10
Lake Hiawatha
Total Phosphorus (cause)
Seasonal Average Patterns Seasonal Average Patterns
Total Phosphorus (cause)
SLIDE 11
Minnehaha Creek
Seasonal Variation Seasonal Variation
Flow Flow
SLIDE 12 Linkage Analysis
Minnehaha Creek
WHAT are the Targets WHAT are the Targets
Parameter
GeoMean (#/100mL) < 10% (#/100mL) E Coli 126 1 260
Lake Hiawatha
126 1,260
Parameter Units
TMDL Target Total Phosphorus μg/L 40 a / 50 b Chloroph ll a g/L 14 Chlorophyll-a μg/L 14 Secchi Depth meters 1.4 Notes:
a WQS Eutrophication Standard b MCWD Water Resources Mgmt Plan Goal
MCWD Water Resources Mgmt. Plan Goal
SLIDE 13
Reduction Targets
Cause Cause – Effect Relationships Effect Relationships
Chlorophyll-a Chlorophyll a
SLIDE 14
Reduction Targets
Secchi Depth
Cause Cause – Effect Relationships Effect Relationships
Secchi Depth
SLIDE 15
Reduction Targets
Critical Conditions Critical Conditions
Interannual Flow Variation Interannual Flow Variation
SLIDE 16
Reduction Targets
Chlorophyll-a
Cause Cause – Effect Relationships Effect Relationships
Chlorophyll a
SLIDE 17
Reduction Targets
Secchi Depth
Cause Cause – Effect Relationships Effect Relationships
Secchi Depth
SLIDE 18 Linkage Analysis
Reduction Needs Reduction Needs
Parameter 2001-2011 Average Target Reduction
301 1 126 58% Total Phosphorus (µg/L) 70.9 40 2 44%
3
p (µg ) 50 3 29% Notes:
1 Average values reflect geometric mean, consistent with WQS. 2 Minnesota Rule 7050 2 Minnesota Rule 7050. 3 MCWD Lake Hiawatha water quality goal.
SLIDE 19 Linkage Analysis
Flow Estimates Flow Estimates
Needed for Load Calculations Needed for Load Calculations
Load = Flow x Concentration x Conversion Factor
Utilize WOMP Gage
Consistent record Consistent record
Key Considerations
Storm water Grays Bay releases
SLIDE 20
Flow Estimates
Base Flow / Stormwater
Hydrograph Separation Hydrograph Separation
Base Flow / Stormwater
SLIDE 21 TMDL Development
TMDL Report -- Required Elements
Regulatory Regulatory Framework Framework
TMDL Report Required Elements
Applicable WQ Standards Loading Capacity Source Assessment Allocations Seasonal Variation Seasonal Variation Margin of Safety
TMDL
W A
WLA
A MOS
TMDL = WLA Point Sources + WLAMS4 + LA + MOS
SLIDE 22
Linkage Analysis
Watershed Loading & Response Watershed Loading & Response
SLIDE 23 Linkage Analysis
Grays
Assessment Points Assessment Points
Grays Bay Lake Hiawatha West 34th Excelsior McGinty 32nd Ave Browndale Upton Chicago
McGinty
SLIDE 24
Allocation Options
Equal Percent Reduction Equal Percent Reduction
SLIDE 25
Allocation Options
Area Export Coefficient Area Export Coefficient
SLIDE 26
Allocation Options
“Combination” Approach “Combination” Approach
SLIDE 27 Minnehaha Creek TMDL
Discussion Discussion
Data Summary Data Summary
Phosphorus reductions needed Bacteria reductions approximate Disproportionate areas of loading
Allocations
Baseline year for MS4 permit Other options ??? Baseline year for MS4 permit
