The Ohio Supreme Court provided a major setback to Ohio EPA efforts to establish water  quality-based discharge limits in its surface water discharge permits (i.e., NPDES permits),  affecting (1) any manufacturer who discharges water directly into surface water or (2) any  political subdivision with its own wastewater treatment plant. The Court determined in Fairfield County v. Nally that Total Maximum Daily Loads (TMDLs) must go through formal administrative  rulemaking before they can be used to support discharge limits in NPDES permits.

Ohio EPA had argued the TMDLs were merely guidance. The Court rejected the Agency's argument and  said that TMDLs establish new legal obligations and, therefore, must go through the formal  rulemaking process contemplated by Ohio Revised Code Chapter 119.


Section 303(d) of the Clean Water Act requires the identification of polluted rivers, streams,  lakes, and other waterbodies. Once impaired waterbodies are identified, the Clean Water Act  contemplates use of the TMDL process to determine the maximum amount of a pollutant that may be  discharged without causing the receiving body of water to violate water-quality standards. See 33  U.S.C. 1313(d)(1)(C).

A TMDL is a complex technical analysis of a waterbody. The analysis includes chemical and  biological testing of the waterbody to determine whether it currently doesn’t meet water-quality  standards. If the waterbody doesn’t meet water-quality standards, the TMDL process  determines how  much reduction must occur in various pollutants for the waterbody to be able to meet water-quality  standards. If the waterbody meets water-quality standards, the TMDL determines how much additional  pollution may be discharged to it before it will no longer meet those standards.

Once the TMDL process determines either the amount of pollutant loading reduction needed or  available pollutant loading remaining, the Agency allocates the available pollutant loading among  the NPDES permitted dischargers to the surface water body (i.e., wastewater treatment plants,  utilities, manufacturers, etc.). The allocation takes the form of effluent discharge limits for  dischargers through NPDES permits.


As of May 9, 2013, Ohio EPA had listed approximately 86 watersheds for TMDL development, and  approximately half had been completed and approved by U.S. EPA. While there are 86 watersheds,  there may be multiple surface waters in each watershed. According to information provided by Ohio  EPA, the Agency has issued approximately 1,761 TMDLs for watercourses throughout Ohio, including  132 TMDLs to determine phosphorus loading alone.

The map below is from Ohio EPA’s website and shows the current status of the TMDL process for each  watershed. The purple areas show those watersheds with TMDLs approved by U.S. EPA. The other colors  show the progress toward obtaining U.S. EPA’s approval of the TMDL.

After the Ohio Supreme Court decision, all of the purple areas will have to through the rulemaking  process before those TMDLs can be used to support discharge limits in NPDES permits for those  watersheds.

Furthermore, any NPDES permit that currently has a discharge limit based upon a TMDL approved by  U.S. EPA is likely not enforceable. Given the large number of NPDES permits that have been issued  in these areas, the Court decision represents a huge setback for the Agency.

Not only does the decision make it more difficult for the Agency to enforce discharge limits in
existing NPDES permits, the Agency will also have to expend significant resources going back 
through the rulemaking process for potentially each the 1,761 TMDLs the Agency had previously
considered completed.

Click here to view the image.