Total Maximum Daily Load (TMDL) Program 

Click on the watershed labels to be taken to their respective pages.                                
Watersheds in Ohio

The Total Maximum Daily Load (TMDL) program, established under Section 303(d) of the Clean Water Act, focuses on identifying and restoring polluted rivers, streams, lakes and other surface waterbodies.  TMDLs are prepared for waters identified as impaired on the 303(d) list in the Integrated Report.

A TMDL is a written, quantitative assessment of water quality problems in a waterbody and contributing sources of pollution. It specifies the amount a pollutant needs to be reduced to meet water quality standards (WQS), allocates pollutant load reductions, and provides the basis for taking actions needed to restore a waterbody.

Information about TMDLs and water quality monitoring are organized by large watershed.  The watersheds are shown in the map to the right.  Watershed names are linked to pages with further information.  Ohio typically focuses on  watersheds in preparing TMDLs.

Click here for a list of TMDL project contacts.

For a map of TMDL project progress as of May 2013, click here.

What is a watershed?

A watershed is the area of land that drains into a lake or stream. Watersheds can be small - like the area that drains into the creek behind your house. Or, watersheds can be large - consider all the land, streams and rivers that drain into the Ohio River or Lake Erie.

Ottawa River (Toledo area)

Ohio's TMDL Process

Ohio developed a 12-step project-management-based TMDL process to accomplish TMDLs. The process builds on existing monitoring, modeling, permitting and grant programs in an attempt to establish a cycle of continuous improvement of the water quality in Ohio’s watersheds.  The process, which seeks public involvement in problem-solving and decision-making, contains four broad, overlapping phases:

  • Assess waterbody health: biological, chemical, habitat
  • Develop a restoration target and a viable scenario
  • Implement the solution: inside/outside Ohio EPA
  • Validate to monitor progress: delist or relist.

To gain the perspective of interests outside Ohio EPA, an external advisory group of about 80 people met for over a year to discuss options and recommend how Ohio should approach TMDLs. Their recommendations to the director of Ohio EPA in June 2000 addressed the listing process, how TMDLs should be developed and implemented, and how Ohio should deal with special problems such as mercury and air deposition.

Additional information about TMDLs is available on the U.S. EPA TMDL Web site.

  • April 18, 2013  Ohio EPA is providing for public review and comment the draft Ottawa River (Lima Area) Watershed Total Maximum Daily Load (TMDL) Report, which has been developed in fulfillment of Section 303(d) of the Clean Water Act.  The public review period ends on May 20, 2013.
  • July 12, 2013  The Moxahala Creek Watershed Total Maximum Daily Load (TMDL) report was approved by U.S. EPA on July 10, 2013.