Mosier Council to Hear Report Alleging Illegal Sewer Dumping
The Dalles, Ore., June 26, 2026 — Mosier City Council members will receive a report Wednesday documenting repeated high-pH wastewater events, unusual discoloration and elevated solids entering the city's wastewater treatment plant—conditions operators say suggest illegal dumping into the municipal sewer system.
The council meets at 6 p.m. July 1 via Zoom.
Council members will receive the city's second-quarter water and wastewater operations report from Treatment Equipment Company, which documents several unusual conditions at the wastewater treatment plant.
According to the report, the facility has continued to experience problems with fats, oils and grease (FOG) entering the treatment system. Operators also reported multiple instances during the quarter in which incoming wastewater exceeded a pH of 8.5, turned reddish, pink and white, and carried solids loads that appeared significantly higher than in previous months.
"All these factors lead us to believe that illegal dumping of flows and solids into the Mosier collection system is happening," the staff report states, adding that illegal dumping into the sewer system is a felony offense and should be reported if observed.
The report does not identify the substance or source of the suspected dumping.
Despite those concerns, the wastewater treatment plant remained in full compliance with state permit requirements during the quarter. Operators reported 99% removal of biochemical oxygen demand (BOD) and 98% removal of total suspended solids (TSS), exceeding the required 85% reduction standard. The report states the plant met all permit-required testing with no instances of noncompliance. Staff also reported the facility has operated 546 consecutive days without a lost-time accident.
The quarterly report also highlights several operational issues affecting Mosier's drinking water system. Operators documented recurring low-pressure events, communication failures between control systems, power interruptions, under-voltage conditions and a valve failure at Well No. 4 while construction continues on the city's new Well No. 5. The report notes that all bacteriological water quality tests showed no detectable contamination.
Councilors will also hold a policy discussion on implementing Mosier's new Stormwater Management Plan. Representatives from Willamette Partnership will present the next step in the process: translating the plan into city ordinances governing future development. The presentation outlines the codification process, summarizes proposed ordinance changes and identifies key policy questions for council discussion before formal regulations are drafted.
City Manager Andrea Rogers will provide an update on the city's request-for-proposals process for engineering and planning services.
City Recorder Amy Szilagyi is also scheduled to present a formal artificial intelligence policy for city operations. While the agenda lists the policy discussion, no draft policy is included in the packet available to the public.
The meeting will also include approval of the June 3 council meeting minutes, public comment and routine city updates.
