Oregon Court Upholds Medford Wastewater Permit's Nutrient Limits, Rejects Backsliding Challenge Under Clean Water Act

SALEM (LN) — An Oregon Court of Appeals panel on Tuesday affirmed the Environmental Quality Commission's approval of a renewed wastewater discharge permit for the City of Medford, rejecting Northwest Environmental Advocates' arguments that the permit's nutrient limits fall short of state water-quality standards and that stripping a categorical pollution prohibition from the old permit violated the Clean Water Act's anti-backsliding doctrine.

The Medford Regional Water Reclamation Facility discharges treated wastewater into the Rogue River, which the EPA had listed as impaired for exceeding the state's biocriteria standard — a rule requiring that waters "be of sufficient quality to support aquatic species without detrimental changes in the resident biological communities" — while the facility operated under its prior 2011 permit. Studies tied the impairment to elevated nitrogen and phosphorus discharges.

The 2021 renewal permit responded with a ratcheting schedule of effluent limits: a final average monthly nitrogen cap of 850 pounds per day and a final average monthly phosphorus cap of 100 pounds per day, each applying from April through October — reductions the agency calculated at 75 percent and 80 percent from then-current discharge levels, respectively.

Northwest Environmental Advocates argued the methodology behind those limits was scientifically unsound, contending that DEQ's use of nutrient concentration data drawn from waterways across Oregon and surrounding states — rather than the two nearest ecoregions — produced target concentrations too high to address the river's impairment, and that adjusting phosphorus levels upward rather than pushing nitrogen lower would fail to control cladaphora, an algal species already present downstream.

The court declined to second-guess the agency's expert-weighing. Citing the principle, drawn from prior Oregon precedent, that "a simple conflict in evidence is not a sufficient basis for this court to conclude that the [agency's] findings * are unsupported by substantial evidence," the panel held that the commission had rationally explained its conclusion that NWEA "did not present sufficient evidence to overcome DEQ's use of the 6:1 total nitrogen-total phosphorus ratio to adjust the target phosphorus concentration level upward."

The anti-backsliding claim fared no better. The 2011 permit had barred discharges or activities that "cause or contribute to a violation of water quality standards in OAR 340-041 applicable to the Rogue Basin." DEQ dropped that language from the 2021 renewal. NWEA argued the omission violated 33 USC § 1342(o), which bars permit renewals containing effluent limitations less stringent than those in the prior permit. The court rejected that argument by pointing to the U.S. Supreme Court's 2025 decision in City and County of San Francisco v. Environmental Protection Agency, 604 US 334 (2025), which held that agencies administering the Clean Water Act are not authorized to include such end-result requirements in NPDES permits — making the removed language impermissible in the first place and its deletion legally inconsequential.

On the question of expert testimony, the court held there was no abuse of discretion in the commission's admission of opinions from DEQ Water Quality Program Manager Ranei Nomura, a former permit writer with about nine years in her current role, and Dr. Annear, a civil and environmental engineer whose work experience includes hydrodynamic and water quality modeling to support clients with regulatory permits. Even if Annear had not personally used the N-STEPS dataset at issue, the panel held that his broader water-quality modeling experience was sufficiently related to satisfy Oregon's administrative evidence standard.

The court also turned away a threshold exhaustion challenge from DEQ and the city, who argued NWEA forfeited its claims by not petitioning the commission for administrative review before seeking judicial review. The panel held that because the agency's own rules and proposed order indicated that parties may — but are not required to — file such a petition, and because NWEA had raised its core arguments before the administrative law judge, the group had adequately exhausted its remedies.

NWEA did lose one piece of its fifth assignment: its argument that the commission failed to adequately explain in the final order how it weighed competing expert testimony was held unexhausted, because the group forwent its opportunity to raise that specific objection when it elected not to file exceptions.

Judge Egan authored the opinion, joined by Presiding Judge Aoyagi and Judge Joyce. The Rogue River downstream of the Medford facility remains on the EPA's impaired-waterways list, and the new permit's most stringent phosphorus limit — 100 pounds per day — does not take effect until the end of the permit's ratcheting schedule.