Key Oroville Drain Plugged as Heavy Storms Pounded the Reservoir After a long history of problems, two river outlet valves deep inside Oroville Dam were not operating at a critical time this winter, eliminating one option to help manage severe storm runoff. Written by Matt Weiser Published on ï³ Mar. 8, 2017 Read time Approx. 5 minutes Oroville Dam on February 27, the aftermath of high runoff from several atmospheric river storms. The damaged main spillway is shown at center and the emergency spillway at left. The river outlets are located at the base of the dam on the far right.Photo...