In the case, the court will consider the question of whether the Clean Water Act requires a permit when pollutants originate from a point source but are conveyed to navigable waters by a nonpoint source, such as groundwater.
Maui County injects wastewater into injection wells near the ocean. The wastewater is added to groundwater, much of which then makes its way into the ocean, a navigable water body. The question is whether this “indirect” discharge requires a National Pollution Discharge Elimination System (NPDES) permit.
A permit is clearly required if a discharge is made directly to navigable waters, but lower courts have split on whether a permit is required in this situation. In this case, the U.S. Court of Appeals for the Ninth Circuit found the county needed a NPDES permit.
NGWA and the Water Systems Council filed an amici curiae (friends of the court) brief in the case in May.
The WSC/NGWA brief argues that the release of pollutants by Maui County is covered by the nonpoint source provisions contained in 33 U.S.C. § 1329 of the Clean Water Act. Applying the NPDES provisions in the Clean Water Act to releases to groundwater would both disrespect the clear structure of the act and prove difficult in practice, according to the brief. Other federal and state laws already apply to releases to groundwater and adding the NPDES permit to the list would further fragment an already fragmented system of regulation.
Alternatively, 33 U.S.C. § 1329 contemplates a cooperative effort between the federal government, states, and Indian tribes to address discharges to groundwater. Given the diversity of geology, climate, and use of groundwater resources, states should play the lead role in regulating these releases.
The WSC/NGWA brief contends that if any releases to groundwater require NPDES permits, those releases should be limited to releases to groundwater that flows in identifiable channels or conduits. State water rights often depend on the distinction between percolating groundwater and groundwater in identifiable channels.
A decision by the Supreme Court is expected in early 2020. Amicus briefs and other documents related to the case can be found on the blog of the Supreme Court.