EPA is soliciting comments on the memo released by EPA November 12, 2010 in response to stakeholder concern that input was not obtained prior to the release of the document. The document was developed to provide an update to a 2002 memo that EPA issued on establishing TMDL waste-load allocations (WLAs) for stormwater sources and NPDES permit requirements based on those WLAs. The 2002 memo generally preserved EPA's historic position that numeric water quality-based effluent limits for stormwater sources are neither necessary nor feasible. The 2010 memo was issued to be a revision to the 2002 memo and discusses the use of numeric water quality-based effluent limits in stormwater permits, including surrogates such as stormwater flow volume or amount of impervious cover. EPA also mentions that the possibility of states to disaggregate the WLAs assigned to stormwater sources in TMDLs. Previously, EPA allowed states to provide gross or aggregate WLAs for all stormwater sources. On another point, EPA discusses the option for states to more actively exercise their residual designation authority to regulate previously unregulated stormwater sources.
The 2010 memo was released to the surprise to many in the water sector, as no public engagement was made prior to the document’s release. Specific stakeholder concerns have focused on the application of numeric effluent limitations in stormwater permits. While the EPA has claimed that the memo does not intend to result in a widespread use of this practice, some stakeholders are concerned that end-of-pipe numeric effluent limitations will be placed on every outfall in a municipal separate sewer system. Comments will be accepted through May 16, 2011 and EPA plans to make a decision by August 15, 2011 to either retain the memorandum without change, to reissue it with revisions, or to withdraw it. WEF will be developing and submitting comments through the Government Affairs Committee Stormwater Workgroup.