DWR opens new Oroville Dam spillway for second time

OROVILLE — The California Department of Water Resources began releasing 15,000 cubic feet of water per second from Lake Oroville on Friday in anticipation of the incoming stormwater expected through the weekend.

Much of the release came from the dam’s rebuilt spillway as well as the Hyatt Power Plant.

Ted Craddock, deputy director of the State Water Project, spoke during a press conference in the hours leading up to the spillway release breaking down some of the numbers surrounding the storm and why DWR opened the gates. On Thursday, Craddock said DWR was expecting inflows up to 70,000 cfs but said Friday that the expectations were only up to 40,000 cfs.

“(Lake Oroville) is currently at 2.7 million acre-feet, which is an increase of 1.7 million acre-feet since Dec. 1, before the storms in December and then the current storms that we’re seeing,” Craddock said. “The lake elevation has also risen 180 feet since Dec. 1, which is currently at an elevation of about 840 feet, and 60 feet below the maximum elevation of the lake.”

During wet winters, Lake Oroville is used for flood control and space is kept for high inflows in an effort to avoid damage downstream.

“The State Water Project is closely monitoring the storms and the upcoming storms,” Craddock said. “And as of Wednesday, we began increasing releases out of Lake Oroville to preserve storage for flood protection.”

The first time the new spillway was utilized was in April 2019, when DWR let out 25,000 cfs. According to DWR, the spillway has an outflow capacity of 270,000 cfs.

Craddock said the weather will likely make for a full lake going into spring allowing for more recreation opportunities.

“We’re expecting the lake to reach full capacity for later this spring and summer which will provide opportunities for using the lake while it’s full,” Craddock said.

Weather ahead

Since Tuesday, the valley around Chico has seen roughly 0.43 inches with higher elevations such as Stirling City getting as much as 4.5 inches, said National Weather Service meteorologist Erik Kurth.

The storm system through the weekend is expected to bring up to an inch and a quarter of rain for valley areas with that number creeping up to between two and three inches for foothill areas.

“This first atmospheric system has had much of the heavier rain pushed southward but we’re still getting some showers,” Kurth said. “There will be a bit of a lull (Friday) evening and then by the early morning hours on Saturday we will see rain showers returning to the area.”

Kurth said there is some potential for thunderstorms in the southern parts of Butte County that could work toward the northern end.

In addition to weekend storms, Kurth said a second atmospheric river is expected to come through on Monday and stay through Wednesday with even more rainfall.

“The next system on Monday and Tuesday could see higher amounts such as two to three inches for Chico with four to six inches for the foothills,” Kurth said.

Kurth said there will likely be a break in the storms March 16 with a small possibility of another system next weekend, though he added that it’s still too far out to know for sure.