Please join us to learn the results of the project!!

Transcription

1 Wirth Lake Excess Nutrients TMDL Public Notice Meeting When: June 24 th, 5:30 p.m. 7:00 p.m. Where: Theodore Wirth Park, Wirth Golf Chalet, 1339 Theodore Wirth Pkwy. Minneapolis, MN Why: The Minnesota Pollution Control Agency, the Bassett Creek Watershed Management Commission and the Minneapolis Park and Recreation Board invite you to attend a meeting to discuss the results of the Wirth Lake Excess Nutrients TMDL project (visit the project info.) Section 303(d) of the Clean Water Act requires states to develop Total Maximum Daily Loads (TMDLs) for water bodies that are not meeting water quality standards. The TMDL process establishes the allowable loading of pollutants for a water body. Wirth Lake is listed on the 2004 Minnesota Section 303(d) List of Impaired Waters due to impairment of aquatic recreation by excess nutrients (phosphorus). Since August of 2008 the Minnesota Pollution Control Agency, the Bassett Creek Watershed Management Commission, the Minneapolis Park and Recreation Board and Barr Engineering have been working together with a local technical advisory team to produce a TMDL. Please join us to learn the results of the project!! Contact Information: Brooke Asleson, Project Manager, MPCA brooke.asleson@state.mn.us wq-iw11-03t

2 Wirth Lake Nutrient Impairment Total Maximum Daily Load (TMDL) Study Public Meeting Barr Engineering Company June 24, 2010

3 Outline Existing lake water quality relative to standards Watershed and lake water quality modeling Calibrated to existing conditions Used to determine allowable load/develop allocations Recommended load reduction alternatives/implementation strategies TMDL Report and next steps

4 Current water quality

5 Historical water quality

6 Historical water quality

7 Historical water quality

8 Current water quality relative to standards d Goals for North Central Hardwood Forests ecoregion 40 ug/l total phosphorus 14 ug/l chlorophyll-a 1.4 meters Secchi transparency Existing lake water quality Met the criteria for all three parameters during five of the last eight years Good relationship between Avg. TP and water year precipitation

9 Critical conditions

10 Watershed/lake water modeling

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12 Wirth Lake outlet

13 Calibrated water quality modeling Phosphorus opou Existing Water Year Load Source lbs. per year percentage Watershed Runoff Bassett Creek Backflow Atmospheric Deposition Internal Load 66 45% 55 37% 6 4% 20 14% Total Load %

14 Pollutant allocations/ Implementation strategies In-lake phosphorus modeling used to determine allowable phosphorus loading Implementation strategies Modeled load reduction alternatives Developed management recommendations for allocations Monitoring program will track effectiveness of implementing water quality improvements

15 Summary of water quality modeling Water Year Existing Baseline Hwy. 55 Pond no Creek Backflow Hwy. 55 Pond & no Backflow Total Phosphorus (ug/l) Chlorophyll-a (ug/l) Secchi disc transparency (m)

16 Allowable phosphorus load determinations Water Year Load (lbs. per year) Phosphorus Source Existing Allocations (TMDL) Watershed Runoff Bassett Creek Backflow Atmospheric Deposition Internal Load Margin of Safety -- 7 Total Load

17 Floodplain modeling/wirth Lake outlet

18 Floodplain modeling/wirth Lake outlet

19 Implementation strategy recommendations Construct lake outlet structure to prevent Bassett Creek backflow top priority BCWMC intends to add this to 2012 Capital Improvement Plan Continue to implement best management practices (BMPs) for all new development and redevelopment Maintain existing BMPs Ongoing water quality education

20 Next steps Finalize TMDL Report Public Notice TMDL Implementation Plan

21 Questions?

22 Wirth Lake Excess Nutrients TMDL project Public Meeting June 24 th, 2010 Minnesota Pollution Control Agency

23 Contro ol Agenc cy Minne esota Pollution The Total Maximum Daily Load (TMDL) Program: A Brief Overview

24 Legal Authority Contro ol Agenc cy Minne esota Pollution Federal Clean Water Act (CWA) of 1972 framework for protecting, restoring water quality Focus: CWA Section 303 establishes national water quality standards and Impaired Waters (TMDL) programs

25 The Impaired Waters List Contro ol Agenc cy Minne esota Pollution 303(d) Lists: Inform/educate the public Ensure that further study of impaired waters occurs (the TMDL Study) Encourage action to restore water quality

26 What is a Total Maximum Daily Load (TMDL)? Contro ol Agenc cy Minne esota Pollution It is a process It is a formula

27 TMDLs The Process Contro ol Agenc cy Assess waters Determine if impaired Place water on 303 (d) list Monitor, study water body further Minne esota Pollution Complete pollutant load allocation formula Develop restoration plan Implement plan Monitor changes in water quality Next steps Delist?

28 TMDL A Mathematical Formula Contro ol Agenc cy Minne esota Pollution A TMDL Study must complete this pollution load allocation formula: LA(s) + WLA(s) + Margin of Safety + Reserve Capacity = Total Maximum Daily Load Where: LA = Load allocations from nonpoint sources WLA = Waste load allocations from point (permitted) sources Margin of Safety = to account for potential scientific error Reserve capacity = set aside for future development

29 The allocation formula determines Contro ol Agenc cy Minne esota Pollution the maximum amount of a specific pollutant that can be discharged to a waterbody and still meet water quality standards

30 TMDLs require technical skills and people skills Contro ol Agenc cy Minne esota Pollution A quantitative analysis which determines the maximum amount of a specific pollutant that a waterbody can safely handle and still meet beneficial uses A collaborative process bringing together Citizens Industry Agriculture Local, state and federal governments Forestry to solve a water quality problem

31 Minnesota Pollution Control Agency Water Quality Standards: A Brief Overview

32 Beneficial Use Classifications Contro ol Agenc cy Minne esota Pollution Use Class Class 1 Class 2 2A 2Bd 2B 2C 2D Class 3 Class 4A Class 5 Class 6 Class 7 Beneficial Use Drinking Water Aquatic life and recreation Cold water fisheries, trout waters Cool and warm water fisheries, drinking water Cool and warm water fisheries Indigenous fish and associated aquatic community Wetlands Industrial uses and cooling Agriculture and wildlife uses Aesthetics and navigation Other uses Limited resource value waters

33 Numeric Water Quality Standards d Contro ol Agenc cy Minne esota Pollution Sets a specific concentration for a certain pollutant in water that will allow maintenance of beneficial uses All use classifications have numeric standards associated with them (except Class 6 other uses) Ideally, if the numeric standard is not exceeded, the beneficial use will be protected

34 Lake Nutrient Criteria Development Contro ol Agenc cy Minne esota Pollution Considers regional patterns & distributions; Varying uses of lakes & differences among deep & shallow lakes; Consider fishery (aquatic life) requirements; Shallow lakes emphasis on plant communities relative to P, chl-a, & Secchi; Use of sediment e cores to re-affirm regional ego patterns & estimate background; Accounts for lake user perceptions; p

35 Minnesota s Lake Eutrophication Criteria Contro ol Agenc cy Minne esota Pollution Ecoregion TP Chl-a Secchi (classification) ppb ppb meters NLF Lake trout (Class 2A) NLF Stream trout (Class 2A) NLF Aquatic Rec. Use (Class 2B) CHF Stream trout (Class 2a) CHF Aquatic Rec. Use (Class 2b) CHF Aquatic Rec. Use (Class 2b) Shallow lakes WCP & NGP Aquatic Rec. Use (Class 2B) WCP & NGP Aquatic Rec. Use (Class 2b) Shallow lakes

36 Wirth Lake (Lake ID ) Contro ol Agenc cy Minne esota Pollution Lake Characteristics Lake Area (acres): Littoral Area (acres): 23 (58%) Maximum Depth (ft): 25 Wirth Lake is classified as a deep lake Lake Water Quality Data Summary Total Phosphorus Mean: 53 ppb (parts per billion) Total Phosphorus Standard Error: 2 ppb Total Phosphorus # of Observations: 78 Chlorophyll-a Mean: 23.5 ppb Chlorophyll-a Standard Error: 1.7 ppb Chlorophyll-a # of Observations: 77 Secchi Disk Mean: 1.6 meters Secchi Disk Standard Error: 0.1 meters Secchi Disk # of Observations: 81 STD = 14 ppb STD = 40 ppb STD = 1.4 meters

37 cy ol Agenc ControThe Wirth Lake Excess Nutrients TMDL: Minne esota Pollution Project Details

38 Project Team Contro ol Agenc cy Minne esota Pollution Minnesota Pollution Control Agency Project Sponsor and Project Leadership Role Bassett Creek Watershed Management Commission (BCWMC) Project Partner and Local Water Resource Management Leader Minneapolis Park & Recreation Project Partner Barr Engineering Technical Expertise

39 Technical Advisory Committee Contro ol Agenc cy Minne esota Pollution Representatives from: BCWMC, Cities of Golden Valley and Minneapolis, Hennepin County, Minneapolis Park and Recreation Board, MN BWSR, Mn/DOT Attended 2 meetings Provided input, data and oversight to the project Reviewed and commented on draft TMDL

40 Pollution esota P Minne Project Website Contro ol Agenc cy

41 cy ol Agenc Contro Minne esota Pollution Brooke C. Asleson Project Manager Regional Division-Watershed Section Minnesota Pollution Control Agency phone: (651)