1.0 Introduction and Summary
The Lake Minnetonka subwatershed is located in the central part of the upper Minnehaha Creek Watershed District (MCWD or District), and includes both direct drainage areas to the lake as well as minor subwatersheds. The subwatershed contains all or parts of the cities of Orono, Minnetrista, Mound, Spring Park, Shorewood, Minnetonka Beach, Tonka Bay, Wayzata, Woodland, Deephaven, Minnetonka, Greenwood, Excelsior, Victoria, and Chanhassen. The subwatershed is dominated by Lake Minnetonka, but also includes several smaller lakes and numerous wetlands. Major streams that discharge into Lake Minnetonka include Six Mile Creek, Dutch Creek, Painter Creek, Classen Creek, Long Lake Creek, and Gleason Creek. Lake Minnetonka outlets at the Grays Bay dam into Minnehaha Creek.
Most of the various bays that make up Lake Minnetonka meet or exceed their water quality goals, although there are some bays that fall far short. Only a few of the other lakes have established goals, and limited data is available to assess their water quality. The streams that drain the other subwatersheds in the Upper Watershed convey significant phosphorus and sediment loads to the lake, and are a major cause of the poor water quality in some of the bays. In decades past, several sewage treatment plants operated in the upper watershed, and their discharges conveyed significant phosphorus loads to the lake. Since those plants discontinued operation, the water quality in the lake has improved considerably, but those old discharges may continue to influence water quality from phosphorus in the lake sediments.
Lake Minnetonka is the region’s premier recreational and fishing lake, with an excellent, nationally-recognized bass and sport fishery. Eurasian watermilfoil is a nuisance in several bays and channels, and the Lake Minnetonka Conservation District harvests several areas on a continuing basis. Numerous high-value wetlands are present in the subwatershed.
Over the next ten years, the District’s focus in the Lake Minnetonka subwatershed will be on improving water quality in Lake Minnetonka by improving water quality and reducing pollutant loading in the nine subwatersheds that drain to it. The following will be particular focus areas:
- Improving water quality in Jennings Bay by implementing a series of improvements in he Painter Creek subwatershed to reduce phosphorus and sediment loading conveyed from the subwatershed into the Lake.
- Evaluating options for similarly reducing pollutant loading from the Six Mile Marsh subwatershed into Halsteds Bay and from Classen Creek into Stubbs Bay.
- Creating conservation corridor linkages between the subwatersheds in the upper watershed and Lake Minnetonka.