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USEPA is updating rules to improve the national program for identifying impaired waters, determining the sources of pollution, and designing cleanup plans for those waters. The CWA provides special authority for restoring impaired waters. The Act calls on states to work with interested parties to develop TMDLs for polluted waters. A TMDL is a calculation of the maximum amount of a specific pollutant that a waterbody can receive and still meet water quality standards for its designated use. A TMDL also allocates the maximum amount of each identified pollutant loading that can be contributed from both NPDES permitted point sources (Waste Load Allocation) and nonpoint sources (Load Allocation) into the impaired water. Along with both waste load allocations (WLA) and load allocations (LA) the TMDL includes a margin of safety (MOS) and seasonal variations (SV).


In 1998, the Illinois Environmental Protection Agency (IEPA) identified the West Branch of the DuPage River (West Branch) as impaired and placed it on the state's 303 (d) list requiring development of TMDLs for a number of pollutants of concern (POCs). As a matter of policy, IEPA had previously elected to vigorously pursue the development of TMDLs for the state's impaired waters. IEPA further elected to implement this policy by utilizing outside consultants to develop the TMDLs within the state's prioritized watersheds.

IEPA selected a consultant (CH2MHill) for the West Branch in the winter of 2000 and executed a contract for the development of the TMDLs with the consultant in the spring of 2001. Three of the potential POCs identified by IEPA in the 1998 listing were ammonia, nutrients, and pathogens. Naturally, this grabbed the attention of the Wheaton Sanitary District (WSD) and the other POTWs that discharge into the West Branch.

Nonpoint sources and stormwater point source discharges are not currently limited in the mass of pollutants they may discharge into our nations waters. Because of the “Command and Control” structure of the NPDES program, point source dischargers fear they may have draconian discharge limits imposed upon them within the framework of the TMDL program. It is now recognized that nonpoint source and stormwater pollutant loads probably contribute more to a waterbody's impairment than do POTW dischargers. Adding to this probability, nonpoint source and stormwater pollutant load reduction can not be guaranteed nor easily monitored. Because of the potential mischief this dichotomy presents, Strand met with our client (WSD) in February 2001 to fully discuss the TMDL program and its potential consequences. At the conclusion of this meeting, WSD felt all, or at least most, of the POTWs in the West Branch watershed would also benefit from such a discussion. WSD inquired into the interest the West Branch POTWs and representatives from nonpoint source contributors might have in attending an educational meeting to learn more about the TMDL program. WSD received an affirmative response from many POTWs plus “The Conservation Foundation,” a nongovernmental organization representing the environmental welfare of the entire watershed. Given the level of interest demonstrated by the responses, WSD sponsored an educational TMDL meeting in May 2001.

Document Type: Research Article


Publication date: January 1, 2002

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