Native plants support clean water efforts in Alimagnet Lake

In fall 2024, the VRWJPO completed the first of two planned alum treatments in Alimagnet Lake, a recreational lake split between the cities of Apple Valley and Burnsville. The treatment is intended to reduce in-lake excess phosphorus by binding it to the lake bottom sediments. This initiative has been funded in significant part by Clean Water Fund grants from the Minnesota Board of Water and Soil Resources.

As we’ve documented, the first treatment rapidly improved water clarity. This provided city and watershed staff an opportunity to do more to improve the overall health of the lake before the second alum treatment. Lakes with turbid (unclear) water do not allow light penetration to the lake bottom, which results in limited plant diversity and often an abundance of aquatic invasive (plant) species (AIS). Clearer lakes allow native aquatic plants to grow, which provide food and shelter for fish and waterfowl, help sequester lake nutrients, protect shorelines and lake bottoms, and more.

On August 6, University of Minnesota (UMN) Ph.D. candidates and supporting researchers worked with city staff to plant a suite of native aquatic plants in Alimagnet Lake, trying a new method of native aquatic plant reestablishment intended to combat AIS. Plant species were selected based on extensive research supporting their potential to outcompete existing invasive Eurasian watermilfoil and curlyleaf pondweed following chemical treatment. Native species were planted in the bay on the southeast part of the lake, with fencing surrounding them to alert recreationists to the initiative. UMN research divers will monitor progress in the coming years.