Additional TMDLs in Development
The Wisconsin Department of Natural Resources (DNR) and its partners are working to restore and protect the state's water quality by developing Total Maximum Daily Loads (TMDLs). These multi-year studies involve collecting detailed water quality data, quantifying pollutant sources and creating strategic frameworks to implement necessary reductions.
The following are major TMDL projects in development in Wisconsin. Additional information can be obtained on these and other projects by using the impaired waters search tool or the TMDL project search.
The Lake Pepin TMDL
Total Maximum Daily Loads for Total Phosphorus
The Wisconsin Department of Natural Resources (DNR), together with many partners throughout the basin including the Minnesota Pollution Control Agency (MPCA), is working to improve the surface water quality of Lake Pepin and its tributaries. Lake Pepin is the naturally widest part of the Mississippi River, bordered by Minnesota on the west and Wisconsin on the east. It is located just south of where the St. Croix and Minnesota Rivers join the Mississippi River. Lake Pepin is approximately 21 miles long, averages 1.7 miles wide, and covers 29,295 acres with a maximum depth of 60 feet and an average depth of 18 feet.
Lake Pepin and two small Wisconsin streams that drain directly to it, Lost and Bogus creeks, are listed on Wisconsin’s 303(d) list as impaired due to excessive phosphorus, which leads to nuisance algae growth, oxygen depletion, fish kills, reduced submerged aquatic vegetation, water clarity problems and degraded habitat. This TMDL is designed to complement the TMDL prepared by MPCA for Lake Pepin by addressing Wisconsin’s portion of the Lake Pepin basin. MPCA’s TMDL report, “Lake Pepin and Mississippi River Eutrophication Total Maximum Daily Load Report” was approved by the U.S. EPA on May 19, 2021, and can be found on MPCA’s website.
A copy of Wisconsin’s draft TMDL is available for viewing and comment. Comments and questions can be sent to Kevin.Kirsch@Wisconsin.gov. Comments will be accepted through May 15, 2026. Once finalized, the TMDL will be sent to U.S. EPA for approval.