Crews removing a debris pile, estimated at roughly 1.5 million cubic yards, continue to make progress two days after the Department of Water Resources (DWR) halted flows down the damaged flood control spillway. Debris removal at the base of the spillway will help lower the water level in the channel, key to reoperation of Hyatt Power Plant. The power plant will give DWR an additional way to release water from the reservoir.
Sixty thousand cubic yards of debris have been removed since flows were halted two days ago. Lake Oroville is not expected to rise above 860 feet elevation while spillway flows are halted. That lake level would be 41 feet below the level of the emergency spillway. The current lake level is 843 feet elevation, nearly 60 feet below the emergency spillway. Inflows are roughly 20,000 cubic feet per second (cfs) which has resulted in roughly 3 feet of rise in lake elevation since yesterday.
If Hyatt Power Plant function is not restored within several days, DWR will use the flood control spillway again to regulate reservoir levels.
Once operational, the Hyatt Power Plant can discharge roughly 14,000 cfs, which will allow DWR to better manage reservoir levels through the remaining spring runoff season.
“Our crews are making fantastic progress removing debris from the area,” said DWR Acting Director Bill Croyle. “We are working around-the-clock to get the power plant back online.”
DWR does not expect the anticipated wet weather to interfere with debris removal or to create a lake elevation concern. DWR will continue to monitor the weather forecast as the weekend approaches.
The halt of flows has allowed DWR to better assess the extent of erosion on the flood control spillway that was first noticed February 7. This information is critical to the long-term design of a repair.
Flows necessary to meet fishery requirements in the Feather River downstream of the dam are being maintained at 2,500 cfs through use of water stored in the Diversion Pool and Thermalito Forebay and Afterbay. This complex of small reservoirs just downstream of Oroville Dam will provide enough water to maintain flows for approximately six days.
DWR and the California Department of Fish and Wildlife together are continuing to survey the Feather River downstream of Oroville Diversion Dam and rescuing fish that become stranded in pools as the river level falls. Adult salmon are not expected to be in the river at this time of year. On Tuesday, about 500 juvenile salmon and a few steelhead trout were rescued.
Work continues on the area below the emergency spillway, access roads, and other areas eroded by the emergency spillway runoff. Rock benches and check dams are being constructed to slow water and erosion should the emergency spillway be required to be used again. DWR continues to monitor the status of the dam, spillways, the Hyatt Power Plant and the progress of repair activities. DWR is coordinating with Caltrans to address the impact of emergency response activities on local roads, and this will continue throughout the operation.