Local government and academic groups in Missouri recently filed a lawsuit with the U.S. Environmental Protection Agency (EPA) challenging a total maximum daily load (TMDL) promulgated for Hinkson Creek. Plaintiffs say that the TMDL requires flow reductions of 39.6% at peak conditions but does not identify pollutants of concern. According to plaintiffs, the general flow surrogate requires them to reduce stormwater from all sources, instead of targeting sources that may contain pollutants of concern. In addition, they state that reducing stormwater flow could lower water levels in the creek, concentrating pollutants and actually worsening water quality. The lawsuit will require EPA to provide an explicit connection between stormwater volume and pollutant reduction.

This lawsuit is timely given concerns about flow surrogates raised by industry groups and others during public comment on EPA’s Nov. 12 stormwater memo, which laid out numeric flow limits for stormwater permit holders. Read the Water Environment Federation’s (Alexandria, Va.) comments on the memo here.