9th Circuit: Lawsuit would make agricultural runoff exemption “dead letter”
Published 4:37 pm Monday, September 8, 2025
A federal appeals court has rejected a legal argument that it has determined would render an agricultural exemption to the Clean Water Act a “dead letter.”
The 9th U.S. Circuit Court of Appeals has upheld the dismissal of a lawsuit that challenged the lack of a Clean Water Act permit for an agricultural drainage project in California.
Agricultural organizations feared that if the lawsuit’s interpretation of the Clean Water Act prevailed, irrigated agriculture across the West would face a tremendous new regulatory burden.
Originally filed 14 years ago by fishing and environmental organizations, the complaint alleged the Grassland Bypass Project has violated the Clean Water Act because it discharges non-agricultural pollutants into a wetland along with runoff from irrigated farmland.
The 9th Circuit has now ruled the plaintiffs’ legal theory would make the Clean Water Act’s exemption for “return flows” from crop irrigation a “dead letter,” or meaningless, since it’s “a scientific impossibility” to prevent dust or stormwater from mingling with agricultural runoff.
“We cannot adopt a statutory reading which we know will sap the interpreted provision of all practical significance,” the 9th Circuit said.
Fishing and environmental groups allege the project is one of the “most pernicious sources of contamination” in Northern California waterways, with a “witch’s brew” of various pollutants seeping into its massive drainage system from sediment and groundwater.
Selenium, boron, chromium, radon, mercury, arsenic and salts from non-agricultural sources are thus discharged through the project’s channel, making it a “point source” of pollution that requires a “national pollutant discharge elimination” permit, or NPDES, under the Clean Water Act, the plaintiffs claimed.
These arguments were opposed by the U.S. Bureau of Reclamation and affected California irrigation districts, who argued the plaintiffs’ legal theory would eviscerate the Clean Water Act’s exemption for agricultural runoff.
The Grassland Water District, which helps operate the project, argued that “short of hermetically sealing every agricultural drain or canal, it leaves no way for farmers who irrigate to avoid NPDES permit requirements.”
A coalition of 13 agricultural groups also weighed in on the broader implications of the lawsuit, claiming it went against Congressional intent and threatened irrigated agriculture across the West, which depends on drainage systems to support crop production.
“Subjecting such projects and discharges to the CWA’s NPDES permitting process and requirements would result in increased regulatory burdens, legal liability, civil and criminal penalties, and legal costs imposed on those responsible for a large percentage of our nation’s food supplies,” the agricultural coalition said.
The 9th Circuit has now agreed with these arguments, rejecting the “contention that the commingling of any amount of nonpoint source pollution from a non-agricultural source forecloses the exemption,” as this “position would contravene the text, purpose and structure of the Clean Water Act.”
The exemption for agricultural runoff was specifically created by Congress several years after the Clean Water Act was enacted due to the logistical difficulty of “disentangling” nonpoint sources of pollution — such as dust and stormwater — from agricultural drainage, the ruling said.
The law was also amended to avoid treating farmers differently if they depend on irrigation rather than rainfall, and easing the permitting burden on the federal government, according to the 9th Circuit.
“If Plaintiffs’ theory were correct that for the exemption to apply, irrigation return flows cannot contain any amount of nonpoint source pollution unrelated to irrigated agriculture, then all three of Congress’s aims would be thwarted,” the 9th Circuit said.