Minnetonka

Study Overview:

In 2006, the Nine Mile Creek Watershed District (NMCWD) completed construction of three stormwater detention ponds near Minnetoga Lake. In addition, the district upgraded two ponding areas into stormwater detention ponds. The goal of these improvements was to reduce phosphorus entering Minnetoga Lake.

These management practices were implemented twenty years ago. NMCWD now seeks to conduct a study to evaluate the current health of Minnetoga Lake and determine whether additional improvements are needed.

Recent water quality monitoring indicates that surface water conditions in Minnetoga Lake remain generally good. However, water samples collected at deeper depths suggest that phosphorus released from lake bottom sediments—known as internal phosphorus loading—may be contributing to increased algae growth and declining water quality.

This study will evaluate the extent of internal phosphorus loading in Minnetoga Lake and identify potential management strategies to protect and improve water quality, as needed.

Study Details:

This study will review historical information on water quality, aquatic plants, fish populations, algae, lake levels, and lake-bottom sediments, as well as changes within the surrounding watershed that may influence nutrient runoff.

Consulting staff will assess the effectiveness of past lake and watershed improvement projects, estimate the amount of phosphorus entering the lake from both watershed runoff and lake sediments, and use models to better understand how these phosphorus sources affect water quality and algae growth.

Based on the findings, the study will develop recommendations and cost estimates for reducing internal phosphorus loading from lake sediments.

The results will guide decisions to protect and enhance the long-term health of Minnetoga Lake.

Community Engagement:

Community meeting on July 14, 2026 5:30-7p

Discovery Point 12800 Gerard Drive, Eden Prairie.

Study Timeline:

May 20, 2026- Board of Managers approved the Internal loading scope of work (SOW)

August 5, 2026- Staff will review the Internal loading assessment with the Board of Managers

August 19, 2026- Public Hearing

Questions:

Contact Erica Erica Sniegowski, Administrator, p: 952-658-9024, e: esniegowski@ninemilecreek.org