SWWD is continuing efforts started in 2022, and will be treating Colby Lake, Markgrafs Lake, Ravine Lake, and La Lake for aquatic invasive species (AIS). All lakes have extensive AIS infestations of curly-leaf pondweed (CLP). Colby Lake also is extensively infested with Eurasian watermilfoil (EWM). Colby, Ravine and La lakes are infested lake wide and will have lake wide treatments applied. Only portions of Markgrafs Lake are infested and only those areas will be treated.
As area residents have likely seen, CLP and EWM cause significant nuisance conditions on District lakes making in lake recreation such as fishing and canoeing or kayaking quite difficult. Additionally, CLP in particular disrupts normal lake cycles by growing over winter and spring when there is little competition from native species and then senescing, or dying off, in early summer. When CLP dies off in early summer, it releases nutrients into the water that can then drive ongoing algae blooms through the peak of summer heat.
Fall marks an ideal time to treat CLP as it is just starting its growth cycle for the following year and native species are dormant. However, this treatment marks just a start of ongoing management. In order to make progress on knocking back CLP and EWM, SWWD and its partners expect to continue to treat lakes into the future as long as they prove to be effective at making District lakes more usable for residents. The District also expects to expand efforts to other infested lakes in the District if efforts prove successful.
All in lake plant management is permitted by the MN Department of Natural Resources and performed by licensed applicators. Herbicides for treating in lake AIS infestations have been around for a long time and have been studied extensively. Research has shown that they do not harm fish, mammals, or aquatic insects and are safe for humans and pets. However, signage will be clearly posted to notify lake users of ongoing treatment
YouTube Video on the In-Lake Treatment on Colby Lake
For more information contact SWWD Water Resource Program Manager John Loomis at 651-714-3714 or john.loomis@woodburymn.gov.