http://www.parks.ca.gov/live/lakeorovillesra_spillwaytop

From their community updates:

Following manufacturer’s instructions, new lighting installed on Oroville Dam’s main spillway will remain on for a continuous 72-hour period as part of activation testing. It’s anticipated this testing period will begin during the last weeks of January with some preliminary tests taking place beforehand. The public’s patience is appreciated as DWR complies with the lights’ activation requirements. After testing is complete, the lights will then be used intermittently based on operational needs.