Edina
About
Arrowhead and Indianhead lakes are landlocked lakes surrounded by residential properties in Edina. Recent District lake studies show poor water quality below state standards in both lakes. The Nine Mile Creek Watershed District Board of Managers ordered the Arrowhead Lake and Indianhead Lake Improvement Project in November 2023. The projects on these lakes are designed to improve the water quality by reducing the amount of phosphorus, an algae producing nutrient, in these lakes.
Project Details
The District plans a combination of activities in 2024 to help reduce the nutrients contributing to poor water quality in Arrowhead and Indianhead lakes and improve overall lake health:
In-Lake Aluminum and Iron Sediment Treatment
District water quality studies revealed that most of the phosphorus in Arrowhead and Indianhead lakes is coming from the lake bottom sediments. Adding aluminum and iron into the lake will help chemically trap that phosphorus. When aluminum and iron are present in oxygenated water, phosphorus prefers to stick to those elements rather than be loose in the water column. This effectively traps the phosphorus so it isn’t available for algae production.
Lake Aeration
Aeration on these lakes will increase the oxygen levels in the water. Oxygen is important for the success of the aluminum and iron treatment. When oxygen is present, iron, in particular, will continue to stick to phosphorus. 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
Enhanced street sweeping is street sweeping beyond routine sweeping. Enhanced street sweeping also prioritizes sweeping where the most organic material like leaves and twigs are expected. Collecting organic material from streets before it enters the storm drains that lead to Arrowhead and Indianhead Lakes 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.
Schedule
- Water quality study complete: August 2022
- Feasibility study complete: October 2023
- Project ordered by watershed district: November 2023
- Aluminum and iron treatment: Planned for May 2024
- Aeration system installation: Planned for fall 2024
- Monitoring and evaluation: 2024 and beyond
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 and Indianhead lakes. Previous community meetings were held during the development of the water quality study.
Watershed District Water Quality Presentation
Resources
Arrowhead and Indianhead Feasibility Study Report
Arrowhead and Indianhead Frequently Asked Questions
Questions?
Contact Jordan Wein, Water Resources Project Manager, at 952-800-8307 jwein@ninemilecreek.org