Total Maximum Daily Load (TMDL)

What is a TMDL?

The Total Maximum Daily Load (TMDL) is a science-based approach to cleaning up polluted water so that it meets state water quality standards. A TMDL is a numerical value that represents the highest amount of a pollutant a surface water body can receive and still meet the standards.

The Federal Government, through the Clean Water Act, requires each state to develop a TMDL for all waters identified on their Section 303(d) list of impaired waters.  One of the first steps for improving water quality after a TMDL is completed is to develop a TMDL Implementation Plan. DEQ has named certain federal, state, and local governments and agencies, including cities, counties, and special districts as Designated Management Authorities (DMAs) because these agencies and governments have authority to manage and regulate sources of pollutants that are listed in the TMDL. 

Millersburg was listed as a DMA and has had a TMDL plan since 2008.  In 2022, the implementation plan matrix was updated to comply with new mercury requirements.  A five-year review, which consists of an updated implementation plan for the next five-year cycle (2024-2029) and a DEQ questionnaire, is due on November 30, 2023.