Ohio EPA finalizes TMDL for Lake Erie’s Western Basin

It was a long time coming, but the Ohio EPA has presented a final Total Maximum Daily Load (TMDL) report for the Western Basin of Lake Erie to the U.S. EPA.  The agency submitted the “Maumee Watershed Nutrient TMDL ” report on June 30, 2023.  This was the exact deadline agreed to in the Consent Decree that settled litigation against the U.S. EPA and Ohio EPA over the lack of a TMDL for Lake Erie’s Western Basin. 

What is a TMDL?

A TMDL provides a framework for future decisions that affect water quality in waters designated as “impaired waters” that fail to meet water quality standards.  The Ohio EPA declared Western Lake Erie waters as “impaired” in 2018, and the TMDL is the plan for addressing shoreline and open water impairments in the basin.  According to the Ohio EPA, the TMDL report “identifies the links between the waterbody use impairment, sources of impairment, and the pollutant load reductions needed to meet water quality standards.”

How will it affect Ohio agriculture?

A major source of the impairment in the Lake Erie Western Basin is cyanobacterial harmful algal blooms caused by high phosphorus loads.  The report identifies many sources of phosphorus that contribute to the impairment, with the largest component being “nonpoint” sources that include row crop commercial fertilizers and manures.  “Point” sources of phosphorous sources include water treatment facilities; stormwater discharges; and home sewage treatment systems.  The TMDL calls for phosphorus load reductions in the Maumee watershed to remedy the lake’s impairment.  Agriculture would be affected by increased emphasis on management practices for agricultural fertilizers, manures, soils, and drainage. 

How does the TMDL address phosphorus reductions?

The TMDL embraces an “adaptive management” approach that involves developing strategies, establishing milestones, implementing strategies, monitoring environmental responses, evaluating progress, and adjusting strategies.  For row crops, the report focuses on management practices such as soil testing and developing a nutrient management plan.  It proposes other agricultural phosphorous reductions from soil erosion management, increasing cropping diversity through rotations and cover crops, reductions of phosphorus applications, edge-of-field management, two-stage ditch designs, and controlled drainage. The report points out that many of the proposed actions have already been underway on farms in the watershed for over a decade, and monitoring, evaluations, and adjustment strategies will continue the progress made to-date. Figure 50 in the report, below, highlights phosphorous reduction strategies.

What happens next?

The U.S. EPA now must review the TMDL and decide whether to approve or disapprove the report.  It has up to 90 days to do so, according to the Consent Decree.  If the U.S. EPA does not approve the TMDL report, it must then prepare a TMDL for the Western Basin. 

How to learn more

Read the Maumee Watershed Nutrient TMDL on the Ohio EPA website, which also includes a fact sheet, appendices, and a summary of responses to public comments on the draft TMDL.