Wastewater Treatment Plant was flooded during an extreme rain event

The City of The Dalles Wastewater Treatment Plant was flooded during an extreme rain event late in the evening of August 9, 2019. The disinfection system was damaged due to flooding and was offline for six hours until early in the morning of August 10, 2019. Emergency repair efforts continue and the disinfection system continues to operate normally at this time.

Test results from a sample taken during the period that the disinfection system was offline confirmed that an E. coli exceedance occurred. The City is required to take a series of samples after emergency repairs were successful to ensure the water quality is safe for contact. Test results to determine current E. coli levels in the wastewater discharged into the river will be available 24 hours after each sampling.

On Saturday August 10, 2019 samples were taken at pre-arranged locations in the Columbia River to determine the effect of the discharge on water quality in the river. Tests on five samples taken between River Mile 186.5 and 189.5 show that E. coli levels at the sample locations were well below bacterial criteria set by the Oregon Department of Environmental Quality for freshwater recreation.

As a precaution, signs will remain in place at locations of public river access until test results show that the discharge from the wastewater treatment plant has returned to compliance. Signs are posted on the Oregon shore of the Columbia River, from The Dalles Riverfront Park to West Mayer Park boat launch. The signs say: “Warning – Contaminated Water – No water contact” and give phone numbers to call for information.

An updated press release will be sent when additional test results are available.

The City is in communication with the Oregon Department of Environmental Quality and local health department officials to coordinate response. Questions can be directed to the Public Works Department office during weekday office hours 7:00 a.m. to 4:00 p.m. at (541) 296-5401.

For updates go to the City website thedalles.org