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TMDLs – Recent EPA Guidance on Setting “Daily” Load Limits


By Larry Kane, Attorney, Bingham Greenebaum Doll LLP

A 2006 decision of the D.C. Circuit Court of Appeals, Friends of the Earth, Inc. v. E.P.A., 446 F.3d 140, held that total maximum daily loads (“TMDLs”), where required under Section 303(d)(1) of the Clean Water Act (“CWA”), must actually set daily pollutant load limitations rather than load limitations based on some longer time period.

TMDLs are required by the CWA for waterbodies where the application of certain technology-based effluent limitations by dischargers is not adequate to implement applicable water quality standards. For such waters, the TMDLs shall be established for pollutants critical to the water quality standards not being achieved at a level necessary to implement such standards, while taking into account seasonal variations and a margin of safety appropriate for any uncertainties in understanding the relationship between effluent limits and water quality.

At issue in the case were NPDES discharge limits set for biochemical oxygen-demanding pollutants and for total suspended solids to assure compliance with water quality standards for dissolved oxygen and turbidity by discharges from a wastewater treatment facility of the Washington, D.C. Water and Sewer Authority (“WASA”). WASA and EPA contended that, given the nature of the water quality parameters at issue, it is more appropriate to set TMDLs consisting of seasonal or annual load limits rather than daily load limits. Friends of the Earth, an environmental advocacy group, argued that the CWA required daily load limits. The Court of Appeals considered the plain meaning of “daily” in the term TMDL to be just that – daily – and gave short shrift to arguments of EPA and others to the contrary. Consequently, EPA and the states are confronted with the task of setting daily load limits for those pollutants and waters where TMDLs are needed, regardless of the difficulty in some cases in correlating a water quality criterion to a daily load. Ironically, as the Court observed, EPA adopted a regulation in 1978 finding that all pollutants are suitable for calculation of total maximum daily loads. Yet, the agency has not seen fit to revise the regulation to exclude pollutants that are no longer considered suitable for daily load calculations.

In contrast to the Friends of the Earth decision, an earlier similar dispute addressed by the Second Circuit Court of Appeals in NRDC v. Muszynski, 268 F.3d 91 (2nd Cir. 2001) resulted in a conclusion by that court that “the term 'total maximum daily load’ is susceptible to a broader range of meanings” than loads calculated on a daily basis. Notwithstanding this disparity between the two Circuits, the U.S. Supreme Court on January 16, 2007 declined to hear an appeal of the decision from the D.C. Circuit.

On November 15, 2006, EPA’s Assistant Administrator for the Office of Water issued to EPA’s regional offices a preliminary guidance memorandum for establishing TMDLs consistent with the Friends of the Earth decision. In view of the split in the Courts of Appeals, EPA recommends that TMDLs be expressed in daily time increments so as to be consistent with the more conservative opinion in Friends of the Earth. EPA nonetheless expresses a belief that some flexibility exists in how daily time increments may be expressed. For example, EPA provides the following illustrations:

  • TMDLs and underlying load and wasteload allocations may be expressed as both minimum and maximum daily loads, or as average daily loads, for parameters such as pH, where such an approach is consistent with the applicable water quality standard.
  • Also, if consistent with applicable water quality standards and technically appropriate, a TMDL and underlying load and wasteload allocations may include several maximum daily load limits that would apply to different seasons or differing flows in receiving waters.
  • If a TMDL is expressed in terms of a pollutant concentration, it may be appropriate to provide a table or graph to describe the TMDL as daily loads for a range of possible daily stream flows.

EPA does not recommend in its preliminary guidance that States take time away from the priority task of continuing their development of new TMDLs in order to revise existing TMDLs that do not contain daily loads consistent with the preliminary guidance. However, for TMDLs currently under development, EPA recommends that they be revised, if feasible, to be consistent with the guidance prior to their adoption.

Additional technical guidance is expected from EPA to address how to translate water quality criteria into “daily” load limits for various parameters, beginning, perhaps, with bacteria, TSS, sediments and nutrients using a load duration curve approach that provides daily load amounts corresponding to varying daily stream flows.

Finally, EPA’s preliminary guidance opines that the Friends of the Earth decision does not affect existing regulations, guidance, and policy memoranda addressing how TMDLs and their associated wasteload and load allocations are translated into NPDES permit limitations. In any event EPA takes the position that the ruling in Friends of the Earth is binding only on dischargers located in the District of Columbia.

Stay tuned for further developments on this controversial topic.


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