Centerville Lake Alum Treatment

City: Centerville, MN
Completion Date: Expected 2026
Cost: Approx. $1,057,000
Phase: In Progress
Water Body: Centerville Lake
Funding Sources: Clean Water Fund, Rice Creek Watershed District
Partners: City of Centerville, Centerville Lake Assocation, City of Lino Lakes, Anoka County, Anoka County Parks and Rec

Harmful Blue Green Algae Bloom on Centerville Lake Before Alum Treatment

Centerville Lake Alum Treatment May 2024

Alum Treatment being applied on Centerville Lake May 2024

Centerville Lake Alum Treatment Being Applied May 2024

Centerville Lake is located in the Rice Creek Watershed District that has been facing significant water quality challenges. The lake’s impaired status is characterized by frequent algae blooms and poor water clarity, which have hindered its ecological health and public usability.

The lake is listed as impaired for excess nutrients; phosphorus and chlorophyll-a.

RCWD and it’s partners such as Centerville and Anoka County have completed many projects outside the lake to reduce phosphorous going into the lake such as stormwater ponds, rain gardens, and street sweeping.

Now, we’re working on reducing the phosphorus inside the lake, which after several years of scientific study was determined to be the significant cause of water quality issues in Centerville Lake. This is described as “internal phosphorus loading due to sediment-phosphorus release”, and addressing this is a necessary step in restoring water clarity.

The proposed alum treatment is the selected method to address this internal issue. Inside lake treatments such as alum are not always necessary, but in this specific lake, it is.

This method was selected based on a comprehensive feasibility study that has established that internal phosphorus loading from sediment-phosphorus release accounts for a substantial portion of the lake’s phosphorus amounts, making it the largest contributor to the impairment.

The project will control 178 pounds of phosphorus annually (initially), and 2,637 pounds of phosphorus over the 22 year lifespan. Once this project is completed the lake should finally meet the state nutrient standards.

The proposed alum treatment is a proven and cost-effective method to address sediment phosphorus, making it a high-priority action in the RCWD watershed management plan. The project is expected to restore the ecological balance and public usability of Centerville Lake, making it a critical step to ensure the long-term health and sustainability of this important lake and area.

Centerville Lake Alum Project Timeline 2024 to 2026

Project Updates:

Projects updates will be posted in this section as well as on our “News” page.

12/18/2023: RCWD News Article: Revitalizing Centerville Lake: RCWD Celebrates $954,500 Grant for Phosphorus Reduction Project
3/6/2024: Centerville Lake Alum Treatment Project Public Meeting Scheduled for APRIL 11th 2024. Event details here: Centerville Lake Alum Treatment Public Meeting. Postcard invites will be sent out to the communities member around the lake. Anyone is welcomed.
3/12/2024: Quad Press Newspaper Article: RCWD Moves Forward with Alum Treatment
5/12/2024: The Centerville Lake Alum Project is about to begin! Our contractor, Solitude Lake Management, will be arriving on Monday, May 13th in the afternoon. Alum application will likely begin on Tues, May 14, continuing until about May 23rd.
5/14/2024: Alum Treatment is underway! More info here and pictures below
5/21/2024: The first phase of the Centerville Lake Alum Project is wrapping up.
Our contractor, SOLitude Lake Management, completed their final run of alum application this morning, and will be demobilizing this afternoon. Between May 14 and today, they applied nearly 200,000 gallons of alum, averaging about 26,000 gallons per day. There’s nothing remarkable to report about the application – all went as planned. We will return in the spring of 2026 for phase 2 of the alum application.

RCWD will be monitoring several things on Centerville Lake. First, we will continue our regular bi-weekly water quality monitoring, including nutrients, algae, clarity, and more. Water clarity is already remarkably high following the alum application. We’ll also be surveying aquatic plants later this summer, and each summer for the next few years. We have several years of pre-project surveys, so the comparison should be interesting. Lastly, we’ll collect sediment cores in 2025 and use the information to assess performance of phase 1, and, if warranted, adjust application areas and rates for phase 2.