The California Department of Water Resources has temporarily shut down a power plant at Oroville Dam to make improvements that will increase its capacity for releasing water, officials announced Saturday. The Hyatt Power Plant initially stopped functioning when a massive mound of concrete, earth and debris formed in the channel below the dam’s 3,000-foot concrete spillway, which fractured Feb. 7. State officials were able to get it working again Friday, but it was not pumping water fast enough.