Augusta Lake and Sunfish Lake are recreational lakes in the Minneapolis/St. Paul, MN area. The lakes develop algal blooms during summer and the poor water quality has reduced recreational opportunities at both lakes. Algae require the nutrient phosphorus to grow and survive and excessive amounts of phosphorus is the main cause of the algal blooms and associated reduced water quality. Internal phosphorus loading (leaching from the lakebed sediments) and watershed runoff both contribute phosphorus to both lakes, but the majority comes from the lakebed in these lakes.
Samples from the bottom of the lake confirmed that phosphorus was very high in the sediments and available to be released into the overlying water column. HAB Aquatic Solutions will be conducting buffered alum applications during the week of April 24, 2017. The application produces a “floc” that settles to the bottom of the lake. The floc has sites where phosphorus in the sediments become chemically bound as it leaches from the bottom. The floc effectively intercepts and binds the phosphorus, which makes it unavailable for the algae to use for growth. The goals of the projects are to dramatically reduce the internal loading of phosphorus from the sediments, lower the amount of phosphorus available to algae in the water, reduce the amount of algae and and enhance recreation at the lakes.