Click on the video above or below to see the rare sight of Friant Dam spilling water over its top.
Millerton Lake reached its capacity of 520,500 acre-feet on Wednesday, July 12.
Michael Jackson is the area manager for the federal Bureau of Reclamation, which manages the dam. He says the spillover is about 50 to 100 cubic feet per second.
About 3,500 cfs of Sierra snowmelt is coming out the dam’s lower gates and into the San Joaquin River, which continues to run fast and cold.
Following an average rain year, the water release would be about 500 cfs this time of year.