Water & Drought

Damaged main spillway of Oroville Dam to reopen next week

Oroville Dam’s heavily damaged main spillway is expected to resume releasing water a little more than a week from now as levels continue to rise in the reservoir.

The state Department of Water Resources announced Wednesday that the battered concrete spillway is likely to begin water releases around March 17. At that point, the level in Lake Oroville is expected to have risen to 865 feet. That’s well below the point at which water would go over the adjacent emergency spillway, but several feet above the comfort level established by DWR acting director Bill Croyle.

The lake was at just below 860 feet Wednesday evening.

The main spillway was shut down Feb. 27, after three weeks of relentless and powerful water releases, to allow crews to dredge debris that accumulated in the Feather River channel at the base of the dam after the spillway fractured in early February.

Enough debris has been pulled out to lower water levels in the channel and allow partial operation of the dam’s power plant. The plant is releasing water at about 7,000 cubic feet per second, about half its capacity when fully operational, and is expected to play a big role in keeping reservoir levels in check during spring runoff.

The main spillway fractured Feb. 7, prompting its temporary shutdown. Lake levels eventually rose so high that water streamed over the nearby emergency spillway for the first time in dam history. The emergency spillway quickly eroded, and fearing its imminent collapse, officials ordered the temporary evacuation of 188,000 downstream residents and ramped up water releases over the main spillway to bring lake levels lower.

Dale Kasler: 916-321-1066, @dakasler

Related stories from Sacramento Bee