Do I Need a NPDES Permit for Groundwater Discharge?

Update 11/28/2023: 

In late 2023, US EPA issued new draft guidance concerning when a NPDES permit is required to discharge pollutants to groundwater. The new guidance followed a 2020 Supreme Court decision in the case Maui v. Hawaii Wildlife Fund, and varies greatly from the interpretive statement below. 

Details about new NPDES draft guidance for groundwater discharge ("Maui Guidance").

Original Article Published May 2019 and Updated September 2019

US EPA recently clarified its stance on whether the Clean Water Act’s National Pollutant Discharge Elimination System (NPDES) permit program covers point-source discharges to groundwater. Examples of a point-source discharging to groundwater include leaks from an underground pipeline or a remediation well.

In an interpretive statement posted to the Federal Register on April 23, EPA states its conclusion:

“The (Clean Water Act) is best read as excluding all releases of pollutants from a point source to groundwater from NPDES coverage, regardless of a hydrologic connection between the groundwater and jurisdictional surface water.”

(Emphasis ours)

Read EPA’s full interpretation in the Federal Register.

Is This a New Interpretation from EPA?

Yes and no. While this is EPA’s first official interpretation on this issue, generally, a NPDES permit is not required for common activities that result in discharge to groundwater.

These activities include aquifer recharge, leaks form sewage collection systems, septic system discharges, spills and accidental releases, or coal ash impoundment seepage. In fact, the word “groundwater” is completely absent from the legal text that authorizes the National Pollutant Discharge Elimination System (NPDES) requirements.

That said, two ongoing court cases are challenging EPA’s view of point-source discharges to groundwater. Because of conflicting or confusing interpretations offered in the past, EPA felt a need to clarify its position in writing in advance of the Supreme Court taking up the appeals.

The two cases are:
County of Maui v. Hawaii Wildlife Fund
Kinder Morgan Energy Partners, L.P. v. Upstate Forever

In both cases, the courts determined that NPDES requirements may apply when a pollutant released from a point source to groundwater migrates to navigable waters. While these decisions are being elevated for Supreme Court consideration, EPA will apply the court’s decisions to the Fourth and Ninth Circuits. For all other areas, EPA’s new interpretation applies.  

EPA Protections for Groundwater

This does not mean that groundwaters are not protected under the Clean Water Act or other EPA regulations. Under the CWA, all states may regulate nonpoint source pollution—meaning, broadly speaking, any water pollution not covered by Section 402 of the Clean Water Act (i.e., the NPDES permitting requirements).

Other EPA programs also provide protection for groundwater. The Safe Drinking Water Act (SDWA) boasts an underground injection control (UIC) program and a sole source aquifer (SSA) program to protect groundwater. The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) requires reporting of hazardous substance releases, including those that can reach groundwater.

The Resource Conservation and Recovery Act (RCRA) requires facilities that generate hazardous waste to take steps to prevent releases to the environment, including secondary containment requirements and release reporting.

Clean Water Act & NPDES Training

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Tags: Clean Water Act, EPA, groundwater, NPDES, WOTUS