Isn’t there a new stormwater tank in Spokane? Here’s why downtown still flooded

Heavy rain on Thursday caused severe flooding across the region, especially in downtown Spokane. Several people reached out to KXLY4 asking why the city’s new stormwater tank did not completely alleviate the flooding problems.

RELATED: Here’s a recap of the flooding that swept through the Inland Northwest

Simply put, the Spokane Falls Boulevard combined sewer overlow (CSO) was never designed to handle that much rain in the short of time. Some areas saw up to an inch of rain in just 20 minutes, according to the National Weather Service.

City of Spokane Spokeswoman Marlene Feist said the new CSO is made up of 26 tanks; 23 which are active and three of which are still under construction. The new CSO will ultimately be able to hold up to 2.2 million gallons of combined wastewater.

Fesit said the tanks fill up with the dirtier water first – think oil tainted run-off. Then, the tanks are filled with the ‘cleaner’ water. That ultimately means the ‘cleaner’ runoff gets spilled first.

RELATED: Spokane Falls Boulevard reopens after two years

Feist said all of the water from Thursday could not go to the waste water treatment facility because it would overload the interceptor pipe. If that broke, there would have been an even bigger problem on the city’s hand.

Feist said the end goal for the city would be to have less than 20 overflow events a year and around 10 million gallons of water spilled into the river.

Isn’t there a new stormwater tank in Spokane? Here’s why downtown still flooded

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