FILE - This Saturday, Feb. 11, 2017, file aerial photo released by the California Department of Water Resources shows the damaged spillway with eroded hillside in Oroville, Calif. California water authorities will cut the outflow from the dam to allow workers to remove debris piled at the base of its main spillway. The Department of Water Resources said Sunday, Feb. 26, 2017 it will start gradually reducing outflows from the Oroville Dam in Northern California starting Monday morning and completely stop them by the afternoon. (William Croyle/California Department of Water Resources via AP, File)
This June 23, 2005, aerial photo provided by the California Department of Water Resources shows Oroville Dam, Lake Oroville and the Feather River in the foothills of Sierra Nevada near Oroville, Calif. The concrete spillway that was undermined and developed huge holes in the last few days is at lower left. Release of water from the dam, the damaged spillway and the use of an earthen emergency spillway has caused a temporary evacuation on Sunday, Feb. 12, 2017, of thousands of people downstream. (Paul Hames/California Department of Water Resources via AP)
In this Feb. 11, 2017, photo released by the California Department of Water Resources, water flows over an emergency spillway at the Oroville Dam at Lake Oroville in Oroville, Calif. Water will continue to flow over the emergency spillway at the nation's tallest dam for another day or so, officials said Sunday. (Albert Madrid/California Department of Water Resources via AP)
This Saturday, Feb. 11, 2017, aerial photo released by the California Department of Water Resources shows the damaged spillway with eroded hillside in Oroville, Calif. Water will continue to flow over an emergency spillway at the nation's tallest dam for another day or so, officials said Sunday. (William Croyle/California Department of Water Resources via AP)
This Feb. 11, 2017, photo released by the California Department of Water Resources shows the main spillway, bottom, and an auxiliary spillway, upper, of the Oroville Dam at Lake Oroville in Oroville, Calif. Water will continue to flow over the emergency spillway at the nation's tallest dam for another day or so, officials said Sunday. (Albert Madrid/California Department of Water Resources via AP)
FILE - This July 23, 2015, file photo provided by the California Department of Water Resources shows the Russell Avenue bridge, over the Delta Mendota Canal in Firebaugh, Calif. The drought has caused the bridge to subside until there's almost no space between bottom of bridge decking and canal water surface. A NASA scientist says in a report released Wednesday, Aug. 19, 2015 that parts of California's Central Valley are sinking faster than ever as groundwater is being pumped during the state's historic drought. Land in the Central Valley is sinking so much from over pumping of groundwater that it's now starting to damage the state's vital north-south water project, state officials say.(Florence Low/ California Department of Water Resources via AP, File)
File - This undated file photo released by the California Department of Water Resources shows water making its way south through the Central Valley by way of the California Aqueduct. The California Aqueduct has been ferrying water from the state’s verdant north to the south’s arid croplands and cities since Gov. Jerry Brown’s father was in office half a century ago. But now, amid one of the worst droughts on record, a group of farmers want to route some of that water back uphill. (AP Photo/California Department of Water Resources, Dale Kolke, File)