SPOKANE, Wash. – A heavy rainstorm over the weekend led to a section of hillside near TJ Meenach Drive collapsing, disrupting the city’s stormwater management system.
According to the City of Spokane, the collapse exposed a breach in an overflow catchment at Downriver Park, which diverted stormwater into swales meant to filter out pollutants before they reach the Spokane River.
The city said that the breach happened while the Cochran Basin Stormwater System was undergoing final testing. Though not yet fully operational, the system is designed to direct stormwater through a network of concrete catchment areas, engineered hillsides, and bioengineered swales. Once the swales fill up, overflow drains are supposed to safely divert excess water, preventing the system from becoming overwhelmed.
The city said that the breach caused sediment to fill the swale below the hillside, turning it into a pond-like area. While the system did its job by redirecting water to downstream swales, the pump system still needs to be completed, meaning some areas, like the swales at the new Whitewater Disc Golf Course, weren’t yet operational.
Crews said that they are currently monitoring the site to keep sediment from reaching the Spokane River and are planning repairs to the earthen wall next season. The breach occurred during a rainstorm that dropped about an inch of rain, which is significantly higher than typical rainfall for the area.
Despite this setback, city officials assured the public that the Combined Sewer Overflow (CSO) system is still managing stormwater effectively. The CSO system, which includes more than 20 storage tanks across Spokane, has kept over 99% of stormwater out of the Spokane River since it became fully operational in 2022. According to the city as of Friday, no overflow events were reported at the CSO tanks.
City officials will continue to monitor the situation and expect the Cochran Basin system to be fully functional once remaining work is completed. In the meantime, the public is urged to avoid restricted areas around Downriver Park while repairs are underway.
For more information on Spokane’s stormwater management efforts, visit SpokaneStormwater.org.
