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The U.S. Environmental Protection Agency (EPA) recently released a new policy memo on using numeric effluent limits in stormwater permits in areas with pollutant-impaired waters (to reduce pollutant discharges and address water-quality impairments).  �������ϲʿ���Ԥ�� is encouraged that EPA has, once again, recognized that a best management practice (BMP) or “adaptive management BMP approach” is an effective means of achieving water quality objectives.

A prior 2010 version of the memo was a cause of much concern to �������ϲʿ���Ԥ�� and others because EPA released it unexpectedly (without notice or public comment period), and it emphasized a strong preference for numeric effluent limits, over BMPs, to reduce stormwater runoff through National Pollutant Discharge Elimination System (NPDES) permits and total maximum daily load (TMDL) plans.  The 2010 memo was a strong reversal of prior guidance where the agency recommended that states rely heavily on adaptive BMPs in writing NPDES permits, rather than setting numeric effluent limits.  �������ϲʿ���Ԥ�� worked with the Federal Stormwater Association (Washington, DC coalition) to raise objections, both at face-to-face meeting and in written comments.  (During that same time, EPA promulgated a rule to officially withdraw the numeric turbidity limit for the construction site stormwater runoff.) 

EPA’s 2014 memo replaces its 2010 memo on the same subject.  Specifically, the 2014 memo renews and restores EPA’s support for BMPs.  As further explained in the 2014 memo, EPA’s current emphasis is on “clear, specific, and measurable NPDES permit provisions to help restore impaired waters to their beneficial uses.”  The memo makes a distinction between permits for municipal (MS4) stormwater discharges and permits for industrial (including construction) stormwater discharges.  For stormwater discharges associated with industrial activity, EPA recommends and gives examples of types of narrative BMPs – for example “schedule for BMP implementation, frequency of a practice, or a level of BMP performance” – and says that they should be “supported by documentation.”  EPA also recommends the use of “numeric benchmarks for BMPs and associated monitoring protocols for estimating BMP effectiveness in stormwater permits” -- noting that this “adaptive approach” would prompt the permittee to take additional action, as needed, to protect water quality.  (Exceeding the benchmark would not be a permit violation, but failure to take corrective action would be a permit violation.)

EPA said that it intends to publish a compendium of permitting approaches in state-issued industrial and construction stormwater permits in early 2015.

With regard to permits for MS4 discharges, the memo continues to make reference to numeric requirements “where feasible and appropriate” and “as necessary to meet water quality standards.”  However, EPA makes note that permitting authorities can choose to set a “system-wide requirements rather than … effluent limitations on discharges from individual outfalls.”

Notably, for all permitted stormwater discharges, the EPA memo also withdraws the controversial 2010 guidance on using runoff "flow" as a surrogate for specific pollutants in clean-up plans to restore stormwater-impaired waters – recognizing that stormwater flow is not a regulated pollutant under the law.  This change comports with a significant federal district court ruling that the Clean Water Act did not grant EPA the authority to limit stormwater flow as a proxy for regulating sediment discharges under a TMDL plan to restore the impaired Accotink Creek in Northern Virginia because stormwater flow isn't a regulated pollutant under the law. The EPA did not appeal the decision (Virginia Dept. of Transportation v. EPA, No. 12-775, 2013 WL 53741 (E.D. Va. Jan. 3, 2013).

The memo is specifically directed to directors of the water divisions in EPA’s 10 regional offices; it is a guidance document that does not impose requirements on either EPA regions or states.  But it is an important tool that federal and state writers of NPDES permits and TMDLs will look to in the future. 

Click to read the Nov. 26 EPA memorandum “Revisions to the November 22, 2002 Memorandum ‘Establishing Total Maximum Daily Load (TMDL) Wasteload Allocations (WLAs) for Storm Water Sources and NPDES Permit Requirements Based on Those WLAs.’”

For more information, please contact Leah Pilconis, Senior Environmental Advisor to �������ϲʿ���Ԥ��, at pilconisl@agc.org.