In Green Infrastructure, River and Water Organizations, River Restoration and Protection, Water law, Water policy, Water Pollution, Water Quality

EPA’s Stormwater Rule for Small MS4s

Is your watershed covered by one of the country’s 6,700 small Municipal Separate Storm Sewer (Small MS4) permits? If so, EPA’s proposed rule may affect how polluted stormwater runoff is addressed under the Clean Water Act in your area.

Back in August last year, the Natural Resources Defense Council (NRDC) and Environmental Defense Center (EDC) reached a settlement with EPA setting a deadline for EPA to revise permitting requirements for stormwater from small municipal separate storm sewer systems – the “Small MS4” permitting rules.  This was a follow up to a case that NRDC and EDC filed and won long ago that made clear that small MS4s were impermissibly self-regulating and without adequate oversight or transparency. This current settlement is a follow up and requires EPA to issue a proposed rule by December 17, 2015 (done – see below) and a final rule by November 17, 2016.

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Source: Ilya Andriyanov/

When the National Research Council published its landmark review of EPA’s stormwater program in 2009, one of the chief conclusions was that municipal stormwater permits have failed to protect water quality because:

“Most dischargers have no measurable, enforceable requirements. Instead, the stormwater permits leave a great deal of discretion to the regulated community to set their own standards [and] develop their own pollution control schemes ….Significant changes to the current regulatory program are necessary to provide meaningful regulation of stormwater dischargers….”

This finding echoed the legal conclusions of the federal appeals court in the NRDC/EDC case which, six years earlier, had ordered EPA to strengthen its permitting rules for storm sewer systems in municipalities with a population under 100,000 (“Small MS4s”).

Shortly before Christmas, in response to this legal action EPA proposed the new rule that would change the permitting requirements. The proposed rule has been published in the Federal Register and comments on the rule are due on March 21, 2016. Given that EPA dropped their earlier work to issue a broader new post-construction stormwater rule, this recent NRDC/EDC settlement now provides an opportunity improve the permitting rules for a portion of stormwater permits – the small MS4s.

What does it mean?

To learn about the rule, please listen in to our River Network webinar, featuring Debora Clovis, from EPA, and Larry Levine from NRDC explaining the rule and its implications.

Basically, EPA has proposed three different options for changing the permitting for small MS4s.

  • Option 1 – The “traditional general permit approach.” Each small MS4 permit would include all requirements necessary to meet the standard of “reducing pollutant discharges from the MS4 to the maximum extent practicable, to protect water quality, and to satisfy the appropriate water quality requirements of the CWA.” Permittees then must comply with the state permit via a Notice of Intent (NOI).
  • Option 2 – This is the procedural option and would keep the existing permitting structure but the permittees would have to submit more details in their NOI and those would be subject to review and approval by the permitting authority; and
  • Option 3 – the hybrid option, where the state could choose option 1 or 2 or a hybrid of both.

Letters from environmental groups leading up to the proposal advocated for clear, objective and enforceable standards (like a retention standard), a transparent process that allows for public review and input, and the opportunity to incorporate provisions for water quality-based requirements (e.g. TMDLs).

Submit your comments directly to EPA or contact Katherine Baer to join the conversation with other clean water groups working to develop group comments.


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