The birth of Oroville Dam: Watch 1960s construction of tallest dam in the U.S.
In a development that would ease pressure on Oroville Dam’s badly damaged concrete spillway, state officials say the dam’s power plant may be operational by midday Friday.
The Hyatt Power Plant stopped functioning as a massive mound of concrete, earth and debris formed in the channel below the 3,000-foot concrete spillway, which fractured Feb. 7.
The mound, estimated to contain more than 1 million cubic yards of material, was so extensive it raised channel levels to the point that the plant couldn’t function. While the spillway serves as a critical flood-control valve during California’s rainy season, the plant is the dam’s primary outlet the rest of the year.
The plant, when fully operational, can release water at about 14,000 cubic feet per second. While just a fraction of what the main spillway can release, outflows from the plant would be enough to handle about half the inflow expected as the abundant Sierra snowpack begins melting into the reservoir in coming weeks.
On Monday, officials completely shut down releases from the spillway to give crews time to assess damage and remove some of the debris pile and lower the water level.
State officials said Thursday that approximately 110,000 cubic yards of debris have been removed, and the water in the channel has dropped substantially. Electrical crews have been working to reconnect the power plant to the electrical grid.
Meanwhile, officials at the Department of Water Resources, which manages Lake Oroville, say water levels in the reservoir on Thursday remained comfortably below the lip of the nearby emergency spillway.
Last month, water overtopped the emergency structure, which had never been used before. The hillside below quickly began to wash away, prompting the evacuation of 188,000 residents in Butte, Yuba and Sutter counties.
Ryan Sabalow: 916-321-1264, @ryansabalow