As state officials rush to repair an emergency spillway for the Oroville dam -- just 150 miles (241 kilometers) north of San Francisco -- an 819-megawatt hydropower plant, capable of supplying about 600,000 homes with electricity, remains shut there until authorities judge it is safe to come back online. That’s the equivalent of two natural gas-fired power plants that will need to kick into gear elsewhere in California to make up for the lost supplies, according to Bloomberg New Energy Finance.