EPA Requests Comments on Scope of Clean Water Act Applicability to Groundwater

In a proposed rule published in the Federal Register on February 20, 2018, the EPA announced that it is requesting comments on the applicability of the Clean Water Act to groundwater and other subsurface flows that reach jurisdictional surface water. Jurisdictional water (also called “waters of the United States”) is water that falls within the scope of the Clean Water Act’s jurisdiction. Any “discharge of a pollutant” to jurisdictional water is subject to Clean Water Act regulation and is therefore prohibited unless authorization is obtained, generally in the form of a permit issued pursuant to the National Pollutant Discharge Elimination System (NPDES). Determinations about whether water is “water of the United States” are complex and often made on a case-by-case basis. In the proposed rule, the EPA says it is seeking comments on whether discharges to groundwater (and other subsurface flows) that reach jurisdictional surface water are appropriately regulated by the Clean Water Act.

The lines that determine whether water is “water of the United States” and is therefore subject to Clean Water Act regulation have been unclear and hotly contested by the EPA, the Army Corps of Engineers, and the federal courts, including the US Supreme Court. Determinations are often made on a case-by-case basis. This is true for discharges to groundwater, which are subject to Clean Water Act regulation if the groundwater is determined to flow into jurisdictional surface water by way of a “direct hydrological connection.” A NPDES permit must be obtained, therefore, by a facility that discharges pollutants to a man-made settling basin near a river and allows the pollutants to seep into groundwater that feeds into the river, just as it would if it discharged the pollutants directly to the river instead. The EPA is requesting comments on whether it should clarify its previous statements regarding how the Clean Water Act applies in such scenarios and, if so, how it should go about doing this and what other issues it might consider.

Comments must be received on or before May 21, 2018.


Environmental Protection Agency, “Clean Water Act Coverage of ‘Discharges of Pollutants’ via a Direct Hydrologic Connection to Surface Water,” 83 Fed. Reg. 7,126 (proposed Feb. 20, 2018), https://www.federalregister.gov/documents/2018/02/20/2018-03407/clean-water-act-coverage-of-discharges-of-pollutants-via-a-direct-hydrologic-connection-to-surface.