Lake Minnetonka Direct Infiltration (10-LM) Project
Background
Lake Minnetonka is located in the central part of the upper Minnehaha Creek Watershed District (MCWD). Its subwatershed of 32,515 acres (50.8 square miles) includes numerous bays of Lake Minnetonka. The total surface area of Lake Minnetonka is 21.9 square miles, and the direct drainage areas and minor subwatersheds total approximately 28.9 square miles. Lake Minnetonka contains all or parts of the cities of Orono, Minnetrista, Mound, Spring Park, Shorewood, Minnetonka Beach, Tonka Bay, Wayzata, Woodland, Deephaven, Minnetonka, Greenwood, Excelsior, Victoria, and Chanhassen.
The MCWD’s focus in the Lake Minnetonka subwatershed is on conserving ecological integrity, protecting high value wetlands; and improving the water quality in Lake Minnetonka through management of stormwater runoff volume and pollutant load reductions. The 2007 MCWD Water Resources Management Plan has identified capital projects in this area to achieve regional infiltration (2010-2013).
This project will combine feasibility work for three regional volume reduction projects: North Arm Lake Minnetonka (NA-LM); Gray’s Bay Lake Minnetonka (GB-LM); and Lower Lake South Lake Minnetonka (SLL-LM). These subwatershed units are expected to see significant increases in runoff volumes between 2000 and ultimate development of the area in 2030. MCWD seeks to reduce runoff by implementing opportunities to infiltrate runoff in all three subwatersheds. These infiltration projects will also help achieve the water quality goals of the subwatersheds.
North Arm Lake Minnetonka (NA-LM) does not meet its water quality goals established in the 2007 Water Resources Management Plan of 30 μg/L of total phosphorus (TP). The current in-lake phosphorus concentration on average is 31 μg/L, and is predicted to increase by 2020.
Gray's Bay Lake Minnetonka (GB-LM) does not meet its water quality goals established in the 2007 Water Resources Management Plan of 20 μg/L. The current in-lake phosphorus concentration on average is 21 μg/L, and is predicted to increase by 2020.
Lower Lake South Lake Minnetonka (SLL-LM) does meet its water quality goals established in the 2007 Water Resources Management Plan of 20 μg/L.
Feasibility
This project is currently in the feasibility stage. Feasibility work is being completed by Emmons & Olivier Resources, Inc. (EOR). EOR is working with the MCWD and communities within each subwatershed to identify Best Mangement Practices (BMP) opportunity locations and if these opportunities intersect with city/county government Capital Improvement Projects (CIPs) such as road projects, storm sewer upgrading, etc.
