This spring and summer, the Vermillion River Watershed Joint Powers Organization (VRWJPO) is leading an Alimagnet Lake alum (aluminum sulfate) treatment feasibility study. City of Burnsville and City of Apple Valley natural resources staff are also participating in the process. VRWJPO has hired a consultant, Barr Engineering, to conduct field work, analyze data and help put together the final feasibility report. This report is expected to be completed in July. We are hosting a public meeting on July 20, 2023 where the findings of the report will be presented.

What is an alum treatment?

An alum treatment is a common water quality improvement practice in shallow lakes that have excessive phosphorus and poor water clarity as a result of algae growth. Often times phosphorus is released into the water column from lake bottom sediments during the summer months. When alum is added to the water, it attaches to phosphorus and falls to the bottom of the lake, preventing it from feeding algae and improving water clarity. Increased clarity following alum treatments can also lead to increased aquatic plant growth, which help to keep phosphorus levels in check.

One of the first steps in planning for a potential alum treatment is to conduct a feasibility study, which will determine whether Alimagnet Lake is a good candidate for the treatment, and if it is, how to most effectively apply alum in the lake, and the estimated costs. The study will also look at alternative solutions to improve water quality, other than an alum treatment.

At the public meeting, there will be a short presentation to present the findings of the study and then time for attendees to ask questions or provide feedback on the findings. If alum treatment is determined to be a feasible option for Alimagnet Lake, VRWJPO would anticipate applying for a grant in late summer of 2023 to obtain funding to complete the work. No treatment would occur prior to 2024.

If you have any questions regarding the public meeting, please feel free to contact Caleb at 952-895-4543 or caleb.ashling@burnsvillemn.gov.