Combined Sewer Overflow Upgrades

During large storm and runoff events, raw sewage mixed with rain or snow melt flows directly into the Spokane River through 26 combined sewer overflow control points. Usually unseen to the naked eye, this can happen at 22 outfall locations where corrugated pipe is typically buried and discharges effluent a few feet offshore and underwater.

Unfortunately, 11 of these control points have a history of malfunctioning, discharging raw sewage into the river when the weather is dry. This is also the time when people are more likely to be recreating and river flows to dilute sewage are far less. The culprit is mostly debris plugging up control points (drains) and an aging system that makes monitoring difficult.

The City of Spokane is fixing this dry weather problem by upgrading the city’s system. Three overflow points are being outfitted with control vaults and storage tanks to contain overflows and improve monitoring. The other eight overflow points are receiving interim control vaults to reduce plugging and support quick response until tanks are completed over approximately 8 years.

The City agreed to these measures as part of an agreement negotiated by the Center for Justice on behalf of the Sierra Club.