Edina
Project Overview:
Feasibility studies completed in 2023 identified phosphorus released from Arrowhead Lake’s bottom sediments as a primary source of algae growth and poor water quality. Based on these findings, the Nine Mile Creek Watershed District recommended an in-lake treatment using liquid ferric chloride and liquid sodium aluminate.
The treatment is being applied over approximately 19.9 acres of the lake. The first application was completed in spring 2024, and one additional application may be needed to achieve the full phosphorus reduction goals identified in the feasibility study.
Project Details:
The district plans a combination of activities in 2024 to help reduce the nutrients contributing to poor water quality in Arrowhead lake and improve overall lake health:
In-Lake Aluminum and Iron Sediment Treatment
District water quality studies revealed that most of the phosphorus in Arrowhead lake is coming from the lake bottom sediments.
Lake Aeration
Aeration of the lakes will help ensure that there are adequate oxygen levels in the lake to enhance and prolong the effectiveness of the aluminum and iron treatments.
Enhanced Street Sweeping
Collecting organic material from streets before it enters the storm drains that lead to Arrowhead Lake reduces the amount of phosphorus and other pollutants entering the lakes. The City of Edina has already started sweeping more frequently in the Arrowhead and Indianhead sub-watersheds, the district will assess if more sweeping is necessary.
Goldfish Management
Spring 2025: Arrowhead Lake: Box-net was tested on the lake and no goldfish were captured. It has since been removed.
Nmcwd continues periodic drone surveys for aggregation of goldfish.
Project Updates:
A 2025 Water Quality Monitoring report will be posted here later this month.
Community Engagement:
A community meeting was held on October 9th, 2023, at Edina Public Works. At the meeting, City staff shared the results of the lake level study for flood risk reduction and watershed district engineers shared the Nine Mile Creek Watershed District plans to improve water quality in Arrowhead lake. Previous community meetings were held during the development of the water quality study.
Project Timeline:
- August 2022: Water quality study complete
- October 2023: Feasibility study complete
- November 2023: Project ordered by watershed district
- May 2024: Aluminum and iron treatment -Completed
- October 2024: Aeration system installation -Completed
- Summer 2024: City of Edina and NMCWD partnered to conduct a Goldfish survey in Arrowhead -Completed
- 2024 and beyond: Monitoring and evaluation
- 2024 Water Quality Monitoring Report 2024: Arrowhead Lake
Resources
Arrowhead and Indianhead Feasibility Study Report
Arrowhead and Indianhead Frequently Asked Questions
2022 Arrowhead Fisheries survey REPORT
Questions?
Contact Jordan Wein, Water Resources Project Manager, at 952-800-8307 jwein@ninemilecreek.org