The Nine Mile Creek Watershed District will conduct projects during 2019-2020 to improve the health of Lake Cornelia and Lake Edina.
Lake Cornelia and Lake Edina are shallow lakes with poor water quality that are on the state’s impaired waters list for excess nutrients. The projects will work to control nutrient levels (phosphorous) in Lake Cornelia and Lake Edina.
The District conducted a study of the lakes in 2018-2019 to help address the poor water quality in Lake Cornelia and Lake Edina. The District will look to implement projects in 2019-2020 to improve the health of the lakes, including potentially conducting an alum treatment in the fall of 2019 on Lake Cornelia.
Notice of Public Hearing
The Nine Mile Creek Watershed District Board of Managers will hold a public hearing pursuant to Chapter 103B of Minnesota Statutes, on August 21, 2019 at 6:30 p.m., at the Nine Mile Creek Watershed District Office, 12800 Gerard Drive, Eden Prairie, MN, to receive comments on the Cornelia Lake Alum Treatment Project (Project) and consider ordering the Project. The estimated cost of the Project, which includes two treatments five years apart is $232,000. The project will be funded through a watershed-wide levy.
In-lake Alum Treatment
Alum treatments help control phosphorous levels in lakes. Phosphorous is a nutrient that feeds algae. Alum is applied to lakes using specialized equipment and barges that ensure the precise placement of the material in the lake. On contact with the water, the liquid alum forms a fluffy aluminum hydroxide precipitate called floc. Aluminum hydroxide (the principle ingredient of common antacids such as Maalox) binds with the phosphorus to form a compound that does not dissolve in water. The bound phosphorus can no longer be used to fuel algae growth. As the floc settles to the bottom, phosphorus and particles are removed from the water, leaving the lake noticeably clearer. The floc then forms a thin layer on the bottom. The floc layer keeps the phosphorus from entering the overlying water and makes it unavailable to algae. The result is a reduction in the frequency and intensity of nuisance algal blooms, rather than the total elimination of all algae.
Contact Randy, District Administrator, at 952-835-2078.