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Long Lake Improvement Projects

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Long Lake
About this project: 

This project was initiated in 1989 by the Minnehaha Creek Watershed District (MCWD), with assistance from the Minnesota Pollution Control Agency (MPCA) through a Clean Water Partnership (CWP) grant. The overall project framework include: a diagnostic study to characterize and quantify the causes contributing to the decline in water quality in the lake, the development of numerical water quality goals for the lake, and the determination of performance standards for a plan to improve water quality and achieve the desired goals. A Phase II study was also conducted, which evaluated various alternatives for water quality goals set forth in the diagnostic study. These studies were undertaken with the support of the municipalities contributing runoff to Long Lake, assisted by a citizens advisory committee comprised of representatives of local city councils and other interested parties.

Project Summary

The feasibility study identified three projects that would improve the water quality of Long Lake. The first was construction of a wet detention basins to reduce the annual loading of nutrients and sediment delivered to Long Lake via runoff from the northern watershed. Phase I resulted in the construction of a 4.6 acre two cell pond on the northeast tributary south of Deer Hill Road in Medina (Deer Hill Pond). A 2.6 acre two cell pond south of County Road 6 in Orono (County Road 6 Pond) was constructed for Phase II. 

The second project identified in the feasibility report was alum treatment of Long Lake to seal the lake sediments and reduce internal phosphorus loading. Alum removes phosphorus from the water by forming an aluminum phosphate precipitate or by sorption of phosphorus on the surface of polymerized aluminum hydroxide. By allowing the appropriate amount of alum to reach the sediments, the phosphorus-rich sediments supplying the 'internal loading' can be deactivated for potentially long periods of time, improving the clarity of the lake. 

The third project is the enhancement of existing sedimentation basins in the city of Long Lake or Long Lake Park (not city) to reduce the load of nutrients and sediment to Long Lake from two major storm sewered subwatersheds.

In 1999, the Long Lake Habitat Restoration Project focused on restoring shoreland vegetation over a section of Long Lake's west shoreline in Long Lake Park.

Long Lake Project Specifications

  • Location: Long Lake, Orono and Medina
  • Completed: 1996 (Phase I & II); 1998 (Phase III)
  • Contractor: Carl Bolander & Sons (pond construction)
  • Sweetwater Technology (alum treatment)
  • Engineer: Wenck Associates, Inc.
  • Cost: $2.2 million
  • Funding: MCWD ad valorem tax and communities shared in O&M cost
  • Deer Hill Road Site: 71,1000 cubic yards excavated; 35 acre feet; 4.6 acres
  • County Road 6 Site: 25,000 cubic yards excavated; 15.2 acre feet; 2.5 acres
  • Long Lake Park Ponds/Wetlands Site: 10,000 cubic yards excavated; 4 acre feet; 0.85 acres; fish barriers
  • Alum Treatment: 540,000 lbs to treat 181 acres
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