08-22-1994 Council Packet - Laserfiche WebLink

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r Recommendation :Treat Incoming Water (Reduce External Phosphorus Loadlng ) Most of the runoff entering the lake flows in an unnamed stream nortli of County Road 6 in the Cities of Orono and Medina. This stream contributes about 80°/o of the lake’s external phosphorus load, so improvements here can have a significant effect. Recommended is a state-of-the-art series of three wet detention ponds/wetlands with an average depth of 8 teet across 5 acres. Tliis system will detain incoming w'ater so that sediment and phosphorus can settle out. The design of the system also promotes biological uptake of phosphorus by wetland vegetation. The water will then flow through an existing wetland for further treatment before entering Long Lake. ITie same benefits are anticipated on a smaller scale by expanding, deepening, and connecting two existing wet detention ponds/wetlands in the City of Long Lake park. Rseo:IT-1endation :Reduce NPS Pollution The lake receives no wastewater discharges, and its problems mainly arise from "non-point source (NPS) pollution" carried in runolT from 5,470 acres. A Public Information/Education Program is recommended to reduce non-point source pollution through these strategies: Yard Waste Management--Leaves and grass clippings left in the street eventually reach the lake, carrying phosphorus with it. Recommended are municipal ordinances and public education on alternatives like mulching. It is also recommended that the City of Long Lake continue street-sweeping, with highest priority given to areas draining the most to the lake. Urban Fertilizer Management—Phosphorus in fertilizer can also be washed into the lake, so it is recommended that the residential communities and the public consider using only phosphorus-free fertilizer unless soil tests indicate that phosphorus is needed. Livestock Waste Management-Much of the watershed draining to the lake is used as pasture. It is recommended that livestock areas be managed to reduce animal waste exposure to runoff that enters the lake. Agricultural Practices--Cropland comprises about 20% of the lake’s watershed, and its runoIT carries sediment, nutrients, bacteria, and organic contaminants. Recommended are farming practices like conser\^ation tillage, terracing, contouring, strip cropping, crop rotation, and fertilizer management. Additional Recommendations A Citizens Lake .Monitoring Program is recommended, along with continued monitoring by the District to assess water quality. Once significant improvements are made, it is recommended that tlie Minnesota DNR prepare a Fisheries Management Plan and potentially stock the lake with gamelish. Since the lake’s watershed will be completely developed in 2-3 decades, land use planning is recommended to protect the lake improvements, such as wetland preserv^ation and construction ot detention basins. • For more i.nkor .mation . please call the Mlnnehaha C reek Watershed District at 939-8320 •