Bush Lake

Eurasian watermilfoil and Curly-leaf pondweed, both aquatic invasive species, are present in Bush Lake. Recently Eurasian watermilfoil and Curly-leaf pondweed were reported to have proliferated. To determine the current conditions and the growth potential of Eurasian watermilfoil and Curly-leaf pondweed, the City performed two surveys.

The first was a sediment survey to characterize the lake sediments in the littoral zone around Bush Lake. These data were used to predict potential areas of heavy curly-leaf and milfoil growth. Data indicated the potential for light to moderate curly-leaf growth over most of the littoral zone. However, milfoil appears to have the potential for heavy growth in several areas, mainly in the southern and southeastern parts of the lake.

Lake Soil Fertility Evaluation for Bush Lake (20-page, 3.7MB PDF )

The second was a point intercept survey to characterize the current aquatic plant conditions. Milfoil growth was observed at 41% of the sample sites with heavy milfoil growth observed at only 3% of the sample sites. Curly-leaf pondweed growth was light and sporadic throughout the lake. Comparing current data with previous data from a 2006 U.S. Army Corps of Engineers report it appears the Bush Lake aquatic plant community is fairly stable with typical annual variations.

Aquatic Plant Point Intercept Survey Report for Bush Lake (25-page, 4.9MB PDF )

Graph of water levels at Bush Lake,spring and summer of 2006.

In 1996, the City of Bloomington petitioned the Nine Mile Creek Watershed District to undertake the Bush Lake Basic Water Management Project to address concerns over fluctuating lake levels, flooding impacts on private and public lands, tree loss, and submergence of the majority of the surrounding water quality treatment basins constructed to protect Bush Lake water quality. Bush Lake was a landlocked basin with no natural outlet or ability to naturally address these conditions. The Bush Lake Outlet Basic Water Management Project addressed these concerns by providing a controlled outlet from Bush Lake to Southeast Anderson Lake thereby protecting public and private lands from flooding, improving treatment of storm water runoff, and protecting and enhancing the scenic, recreational and wildlife assets of the lake.

In 1999 a pumped outlet from Bush Lake to Southeast Anderson Lake was constructed and operated to restore Bush Lake levels to more closely match the historic normal water level or ordinary high water level as established by the Minnesota Department of Natural Resources. Water levels are currently maintained to the highest possible elevation while continuing to provide the protection and preservation of natural resources and water quality intended by the project. The Bush Lake outlet does not operate until the lake reaches an elevation of 834.0 and will cease operation when lake is lowered to an elevation of 833.5. These elevations were established after involvement and input from residents, lake users, the Bush Lake Citizens' Advisory Committee, as well as direction from permitting agencies.

To date, the results of the Bush Lake Outlet project and shoreline restoration have been a huge success for the City and Watershed District. The native vegetation is quickly re-establishing along the shoreline providing a unique diverse environment for birds and other wildlife not frequently found in the metropolitan area. This restoration included removal of a number of dead trees that resulted from the prolonged high water levels particularly in areas where public safety was of concern. Most dead trees were left in place as recommended by the Minnesota Department of Natural Resources for additional bird and wildlife habitat. Dead trees provide distinctive, valuable wildlife habitat that should be preserved whenever possible.

The Bush Lake Outlet project provides numerous benefits for the Lake. The stable water level minimizes erosion caused by wave action against unstable shore areas, surrounding water quality treatment basins are able to function properly as they are no longer inundated by high lake levels, flood protection to public and private property has been provided, and a native and diverse vegetative shoreline has re-established benefiting the quality of water in the lake and providing desirable habitat for birds and other wildlife.

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