McMahon Lake was removed from the Federal Impaired Waters List (303d List) in 2018 due to improvements in water quality. State standards for shallow lakes in the North Central Hardwood Forest (NCHF) region for the three lake parameters we track are provided in the following table. If a parameter meets for falls below that standard unit, that parameter is meeting water quality standards.
State Standards for Shallow Lakes in the North Central Hardwood Forest Ecoregion
Secchi Disk Transparency
Greater than 1m
Additional water quality reports and information can be found in Annual Reports.
Water Quality 2005-2021
McMahon lake currently as two aquatic invasive species, Curlyleaf pondweed and Eurasian watermilfoil. The Scott WMO treats the public access bay for curlyleaf pondweed each year as a preventive measure of spreading it to other lakes.
Lake Vegetation Surveys
2007, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021
McMahon Lake June 16, 2020
McMahon Lake May 2022
Studies Specific to McMahon Lake
McMahon Lake Improvement District
McMahon Lake Improvement District (MLID) is a political subdivision of the State of Minnesota and was established by the Scott County Board of Commissioners on March 15, 2022.