Corps to Connect Dam Wastewater System to Umatilla’s Sewer System


The U.S. Army Corps of Engineers’ Walla Walla District will begin construction this summer to connect the McNary Dam wastewater sewer system to the city of Umatilla sewer system.

During the construction effort there will be temporary closures and detours affecting Third Street, West Park, Spillway Park, and the Visitor Center/Juvenile Fish Facility. The Corps will give more specific information on closure details and dates as construction progresses.

Officials at McNary Dam determined through routine maintenance and inspections that the current on-site septic systems for the dam, Visitor Center/Juvenile Fish Facility, and West Park were nearing the end of their service life and would need to be replaced. The decision was made to connect to the city of Umatilla’s existing wastewater system due to current Oregon Department of Environmental Quality (DEQ) administrative rules. Those rules state that if a sewage system is within 4,128 feet of the property, then new DEQ permits cannot be issued for new septic systems.

Utilizing the city’s wastewater system will reduce maintenance of drain fields for the dam, could improve groundwater quality in the area, and allows for any future connections from additional facilities that may be needed.

The Walla Walla District awarded a $3 million construction contract to Crestline Construction Company LCC out of The Dalles to connect McNary Dam’s wastewater infrastructure to the city of Umatilla’s wastewater infrastructure.

The impacts to visitors to McNary Dam are expected to be minimal, but there will be times when roads must be trenched, and restrooms closed while new connections are made. The area impacted by this construction at McNary Dam welcomes approximately 290,000 visitors per year to its parks, nature area and visitor center. McNary Dam provides clean hydropower to the region and allows for sustainable transportation of goods with its navigation lock.