On September 5, 2025, the United States Court of Appeals for the Ninth Circuit (Ninth Circuit) issued its decision in Pacific Coast Federation of Fishermen’s Associations v. Nickels, Case No. 23-15599. The decision interprets the scope of the irrigated return flow exemption under the Clean Water Act (CWA) and concludes that drainage flows from the Grassland Bypass Project conveyed through the drainage system, and discharged into the San Luis Drain, qualifies for the exemption.
The Clean Water Act and the Irrigated Return Flows Exemption
Adopted by Congress in 1972, the CWA prohibits the discharge of pollution from any point source into navigable waters of the United States without a National Pollutant Discharge Elimination System (NPDES) permit. The CWA is limited to regulating the discharge of pollutants from “point sources,” rather than those from “nonpoint sources.” Point sources include any discernible, confined, and discrete conveyance, such as a pipe, ditch, or well. A nonpoint source is one that is untraceable to any single source. Examples of pollution from nonpoint sources include windblown dust, and road and highway runoff.
In 1977, Congress created a statutory exemption to the NPDES permit requirements for point source discharges from irrigated agriculture. 33 U.S.C. § 1342(l)(1) provides:
The Administrator shall not require a permit under this section for discharges composed entirely of return flows from irrigated agriculture, nor shall the Administrator directly or indirectly, require any State to require such a permit.
Factual and Legal Background
The Grassland Bypass Project (Project) is a drainage system in the Central Valley of California that conveys irrigation drainage water through a bypass channel and drain before discharging into the Mud Slough wetland, a navigable water of the United States. Since 1997, the Project has operated under the irrigated return flows exemption.
In 2011, Plaintiffs filed suit against the operators of the Project, alleging the Project was in violation of the CWA because the Project discharges pollutants unrelated to irrigated agriculture and thus does not qualify for the exemption. After over a decade of litigation, the district court concluded under the exemption, irrigated return flows may contain additional pollutants from nonpoint sources and point sources related to crop production. Plaintiffs appealed to the Ninth Circuit.
The Ninth Circuit’s Decision and Reasoning
The Ninth Circuit affirmed the district court’s decision, holding that the exemption applied to the Project because the additional pollutants are from nonpoint sources or a point source related to crop production.
In support of their holding, the Ninth Circuit first reasoned that the text of the statutory exemption left ambiguous whether “entirely” requires every pollutant in an irrigation return flow to be from irrigated agriculture. The Ninth Circuit looked to the legislative history to discern Congress’s intent. A 1977 Senate report revealed that “the word ‘entirely’ was intended to limit the exemption to only flows which do not contain additional discharges from activities unrelated to crop production.” The Ninth Circuit reasoned that since the CWA regulates only point source discharges, irrigated return flows may not contain additional point sources unrelated to crop production.
Second, the Ninth Circuit looked at the congressional purpose of the exemption. Congress created the exemption to: (1) alleviate the Environmental Protection Agency’s burden of issuing permits for every agricultural point source; (2) promote equity between farmers who depend on rainfall and those who depend on surface irrigation; and (3) address the technical difficulties of determining whether agricultural pollutants entered the waterway through a point or nonpoint source. The Ninth Circuit held that Plaintiffs’ interpretation would frustrate all three congressional aims.
Third, the Ninth Circuit held that Plaintiffs’ position would render the exemption a dead letter. The Court reasoned that some amount of nonpoint source pollution, such as windblown dust, will inevitably always commingle with irrigation return flows. If Plaintiffs’ interpretation were adopted, the exemption would have no effect at all.
The Ninth Circuit then analyzed the four alleged sources of pollution that commingled with the Project’s return flows, as alleged by Plaintiffs. The Ninth Circuit held that these sources of pollution originate from nonpoint sources or from a point source related to crop production, and therefore the exemption applied to the Project.
Conclusion
Pacific Coast Federation of Fishermen’s Associations v. Nickels clarified the scope of the irrigated return flow exemption of the CWA. The exemption applies when return flows do not contain additional point source discharges from activities unrelated to crop production and it applies even when other nonpoint source discharges are commingled with the irrigation return flow.
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