Prepared by: Emmons & Olivier Resources, Inc. For the Minnesota Pollution Control Agency and Minnehaha Creek Watershed District MCWD Lakes TMDL – Lake Nokomis, Parley Lake, Lake Virginia, Wassermann Lake February 2011 water ecology community Cover Images Left Image: Yellow and white water lily bed on Lake Virginia Right Image: Yellow water lily MCWD Lakes TMDL – February 2011 Minnehaha Creek Watershed Lakes TMDL: Lake Nokomis, Parley Lake, Lake Virginia, and Wassermann Lake February 2011 Primary Authors and Contributors Minnesota Pollution Control Agency Chris Zadak Minnehaha Creek Watershed District Nat Kale Mike Wyatt Emmons & Olivier Resources, Inc. Andrea Plevan Jennifer Olson wq-iw11-09e MCWD Lakes TMDL – February 2011 TMDL Summary Table EPA/MPCA Required TMDL Summary Elements Page # Minnehaha Creek Watershed District in the Upper Location Mississippi Basin, Hennepin County and Carver County, MN 4 (HUC 07010206). Describe the water body as it is identified on the State/Tribe’s 303(d) list: • Nokomis 27-0019, Parley 10-0042, Virginia 10-0015, 303(d) Listing Wassermann 10-0048 Information 4 • Impaired Beneficial Use(s) - Aquatic recreation • Indicator: Nutrient/Eutrophication Biological Indicators • Target start/completion date: 2003/2008 • Original listing year: 2002, 2004 Class 2B waters, MN Eutrophication Standards, MN Rule 7050.0222 Subp. 4 Eutro- Eutro- Proposed phication phication Site- Parameter Standard, Standard, Specific General Shallow Std Applicable Water TP (µg/l) TP < 40 TP < 60 TP < 50 Quality Standards/ 34 Chlorophyll- Numeric Targets chl < 14 chl < 20 chl < 20 a (µg/l) Secchi SD > 1.4 SD > 1.0 SD > 1.4 depth (m) Lakes the Nokomis, standards Virginia, Parley Nokomis apply to Wassermann Nokomis: 1.34 lbs TP/day (for requested site-specific standard: 2.03 lbs TP/day) 57, 70, 82, Parley: 3.5 lbs TP/day 91 Loading Capacity Virginia: 0.84 lbs TP/day (expressed as daily Wassermann: 0.78 lbs TP/day load) Critical condition: in summer when TP concentrations Critical peak and clarity is typically at its worst condition: 93 Wasteload Allocation Source Permit # TMDL Lakes Parley, Carver County MS400070 70, 91 Wassermann Chanhassen City MS400079 Virginia 82 Hennepin County MS400138 Nokomis 57 Parley, Laketown Township MS400142 70, 91 Wassermann Metropolitan Airports MN0002101 Nokomis 57 Commission Minneapolis City MN0061018 Nokomis 57 Minnehaha Creek MS400182 Parley 70 Watershed District Minnetrista City MS400106 Parley, 70 Emmons & Olivier Resources, Inc. i MCWD Lakes TMDL – February 2011 Nokomis, Parley, Mn/DOT Metro District MS400170 57, 70, 82 Virginia Richfield City MS400045 Nokomis 57 Shorewood City MS400122 Virginia 82 Parley, Virginia, Victoria City MS400126 70, 82, 91 Wassermann Waconia City MS400232 Parley 70 Construction and 57, 70, 82, Various all industrial stormwater 91 Reserve Capacity (and related discussion in NA 44 report) Source LA Non-regulated stormwater various Load Allocation 57, 70, 82, Internal load various 91 Atmospheric deposition various Margin of Safety Implicit MOS: Conservative modeling assumptions 40 Seasonal variation: Critical conditions in these lakes occur in the summer, when TP concentrations peak and clarity is at its worst. The water quality standards are based on Seasonal Variation growing season averages. The load reductions are designed 93 so that the lakes will meet the water quality standards over the course of the growing season (June through September). Summarize Reasonable Assurance MCWD Comprehensive Watershed Management Plan Reasonable Assurance 94 NPDES Phase I and Phase II MS4 permits and SWPPPs Local surface water management plans Monitoring Monitoring Plan included? yes 102 1. Implementation Strategy included? yes Implementation 97 2. Cost estimate included? yes • Public Comment period (dates) • Comments received? Public Participation 95 • Summary of other key elements of public participation process Emmons & Olivier Resources, Inc. ii MCWD Lakes TMDL – February 2011 Table of Contents Executive Summary....................................................................................................................1 1. Background .........................................................................................................................4 A. 303(d) Listings......................................................................................................................................4 B. Lake and Watershed Descriptions .......................................................................................................4 Lower Minnehaha Creek Watershed: Lake Nokomis...........................................................................6 Six Mile Creek Lakes: Parley and Wassermann ................................................................................11 Lake Virginia.......................................................................................................................................18 C. Pollutant Sources...............................................................................................................................24 Role of Phosphorus in Lakes .............................................................................................................24 Phosphorus and Shallow Lake Ecology.............................................................................................25 Phosphorus Sources ..........................................................................................................................27 2. Water Quality Standards ..................................................................................................34 Designated Uses ....................................................................................................................................34 Water Quality Standards.........................................................................................................................34 TMDL Endpoints .....................................................................................................................................34 3. TMDL Derivation Approach..............................................................................................36 A. Pollutant Sources ...............................................................................................................................36 B. Calculation of TMDL Components .....................................................................................................39 Loading Capacity................................................................................................................................39 Margin of Safety .................................................................................................................................40 Wasteload Allocations ........................................................................................................................41 Load Allocations .................................................................................................................................44 Trading or Transfer of Allocations ......................................................................................................44 Reserve Capacity ...............................................................................................................................44 4. Lake Assessments and TMDL Calculations ...................................................................46 A. Lake Nokomis.....................................................................................................................................46 Water Quality Assessment .................................................................................................................48 Water Quality Standards ....................................................................................................................51 TMDL Determination ..........................................................................................................................52 B. Parley Lake ........................................................................................................................................59 Water Quality Assessment .................................................................................................................60 Water Quality Standards ....................................................................................................................64 TMDL Determination ..........................................................................................................................64 C. Lake Virginia ......................................................................................................................................73 Water Quality Assessment .................................................................................................................73 Water Quality Standards ....................................................................................................................77 TMDL Determination ..........................................................................................................................78 D. Wassermann Lake .............................................................................................................................83 Water Quality Assessment .................................................................................................................83 Water Quality Standards ....................................................................................................................86