Water Quality Improvement Projects

Three Rivers Park District’s Water Resources Team is committed to improving the water quality of lakes located within the parks. Staff is regularly checking lakes in the Park District for any water quality concerns. If concerns are identified, a course of action is planned and carried out to improve the water quality.

View of clear water at lake shore

Fish Lake Regional Park

Fish Lake covers 238 acres, offering fishing, boating and swimming to park visitors and area residents. In 2008, the lake was listed on the state’s impaired waters list for excess phosphorus. Excess phosphorus causes algae blooms that turn the water green which negatively affects the suitability of the lake for humans, pets and even wildlife.

Together with the Elm Creek Watershed Management Commission and the Minnesota Pollution Control Agency, Three Rivers’ staff conducted water quality studies at Fish Lake. These studies found that most of the phosphorus affecting the lake’s surface water was being released by enriched sediment at the bottom of the lake. Three Rivers Park District worked with the City of Maple Grove, the Fish Lake Area Residents Association, and the Elm Creek Watershed Management Commission to pursue a strategy to correct the problem and bring the lake into compliance with state water quality standards.

On behalf of the Watershed Commission and with the support of the partners, Three Rivers submitted a grant application through the state’s Clean Water Fund program to treat Fish Lake with a chemical compound called alum. The grant was approved and alum treatment has begun. Alum is commonly used in the kitchen for pickling and by water treatment facilities for treating drinking water. When applied properly, it is safe to use in a lake to control phosphorus released by lake bottom sediment.

Lake Rebecca Park Reserve

Lake Rebecca was listed on the state’s impaired waters list in 1998 for excessive mercury and again in 2008 for excess phosphorus. Three Rivers staff worked with Hennepin County Environmental Services to improve manure and stormwater management by a livestock operation in the lake's watershed. The Park District also used several different methods to treat stormwater from developed areas within the Park. In 2009, Three Rivers staff launched efforts to control the invasive curly leaf pondweed, which is known to damage water quality. And finally, Three Rivers staff carried out an alum treatment on the lake to dramatically reduce the release of phosphorus from highly enriched bottom sediments.

Water quality in the lake has dramatically improved, and the public, as well as regulatory agencies, has noticed. Because of these efforts, Lake Rebecca will soon be removed the state's "impaired waters" list, the first lake in Three Rivers Park District to achieve that distinction.