As Water Leaks Out the Oroville Dam Spillway, Officials Prepare for its First Test

With historic precipitation slamming Northern California in recent months, Department of Water Resources officials have kept their eyes on the Oroville Dam, specifically its spillway. The last time the spillway was used was in February of 2017, when it collapsed, forcing the evacuations of 180,000 residents in the Butte County area. Since then, the spillway has gone through a $1 billion reconstruction.

And that brand new spillway is inching closer to its first test.

Water has now reached the spillway and water is seeping out of its gate, showing the first sign of its effectiveness. Officials have increased water flows out of the Hyatt Powerplant from 5,000 cubic feet per second to 7,000 cfs, with hopes to avoid using the spillway. But continued rain may force their hand.

Lake Oroville was at 817 feet elevation on Wednesday, approximately 67 percent of its total capacity. Weather projections show the lake reaching 835 feet on March 15. While those numbers cause the spillway to leak, they are perfectly normal. DWR plans to keep the lake levels at 848 feet through spring and summer for recreation and water storage purposes.

The newly minted spillway is a state of the art tool for the DWR, that according to them, can handle flows of up to 270,000 cfs. DWR maintains they will likely not need to use the spillway in upcoming days, but depending on March weather, may need to use it later this winter.

But DWR officials aren’t the only ones invested in the functionality of the new spillway. For Butte County residents living downstream, with the fiasco of 2017 still close on mind, they continue to keep a close eye on water levels.