Many of us are familiar with TMDLs, or Total Maximum Daily Loads.  But why do some streams have TMDLs while others don’t? 

When monitoring or sampling results over a designated period of time reveal problems with the physical, biological and/or chemical conditions of a stream, river or lake, a waterbody can be listed on a state’s Impaired Waters List.  A revised Impaired Waters List, or “303(d) List”, is typically submitted to EPA every 2 years.  A 303(d) List will have a specific “impairment”, or problem, associated with the waterway, along with the pollutant that is most likely contributing to this problem.  TMDLs are studies to determine the maximum amount of these pollutants that can be discharged to the impaired waterway and still meet water quality goals and support habitat.  TMDL’s provide targets for restoration planning and for regulatory limits in wastewater, storm water, and other permits that allow discharges of pollutants to an impaired waterway.    

With strategic planning, implementation and monitoring, an impaired waterway can be re-monitored and “de-listed”, or taken off the 303(d) List.  This is the declaration that a stream, river or lake is once again healthy and supporting fishable, swimmable activities.

Many states, including Illinois and Wisconsin make the 303(d) lists available online.  Check out these lists to determine if a stream, river, or lake near your community is listed as an “impaired” waterway.


About the Authors

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Maureen A. McBroom
Environmental Coordinator

Maureen is dedicated to the protection and improvement of Wisconsin’s resources through close collaboration with municipalities and their citizens.  Efficient & effective implementation, driven by strong relationships and communication, are drivers behind her project implementation strategies.  She has experience in the WDNR’s Runoff Program, specifically issuing WPDES Permit coverage for construction site erosion control & long-term storm water plans, industrial storm water sites and municipal separate storm sewer system (MS4) permittees. Maureen has been with R/M since 2015.

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