New EPA Draft Guidance at Odds with Stormwater Infrastructure

On December 27, AGC commented (coalition letter) on the U.S. Environmental Protection Agency’s (EPA) draft guidance on when discharges to surface waters via groundwater would require a Clean Water Act section 402 permit (National Pollutant Discharge Elimination System or NPDES). AGC’s primary concern is that the new guidance would lead EPA to consider prevalent stormwater infrastructure (such as sediment basins or retention ponds) as point sources requiring a NPDES permit. These stormwater controls are themselves often required by NPDES permits.

As previously reported, the Biden Administration rescinded earlier guidance issued in January 2021 after the U.S. Supreme Court's decision in the County of Maui, Hawaii v. Hawaii Wildlife, 2020.  In Maui, the Supreme Court laid out seven factors for permitting authorities to consider whether an addition of pollutants to groundwater is the “functional equivalent” of a direct discharge of pollutants to a WOTUS.  The Supreme Court determined “transit time and distance traveled” to be the most important factors in most cases.

In addition to the conflict with stormwater infrastructure and associated risk introduced, the coalition letter also provides corrections needed in the draft guidance, summarized below.

  • Conveyance by groundwater does not create Clean Water Act (CWA) regulatory authority.
  • The guidance should not apply to the movement of water through the unsaturated zone; water percolation through the unsaturated zone is not a flow.
  • A mere increase of a pollutant does not in itself establish functional equivalence.
  • “Constituents” is not a substitute for pollutants under the CWA; unpermitted discharges of pollutants are prohibited by the Act.

For more information, please contact Melinda Tomaino at

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