The state Department of Water Resources has started using laser and sonar technology to measure reservoir capacity, determining that Lake Oroville, the State Water Project’s largest reservoir, has shrunk since its creation in 1960.
In 2021, the DWR used laser pulses mounted on an airplane to map parts of the basin’s terrain that were not underwater at the time due to historically low lake levels. Following that, in 2022, a boat sent sonar pulses into Lake Oroville to map the underwater terrain. Engineers calculated that the reservoir had 3% less capacity — over 100,000 acre-feet — than previously estimated.
“You could even detect the old intact roadways and train tracks that were used during the dam’s construction in the ’60s,” said Tony Squellati, manager for the photogrammetry and computer mapping unit of DWR’s Division of Engineering-Geomatics, in a news release.
The change in lake volume can be attributed to sediments such as rock and silt accumulating on the lakebed floor in the six decades since the construction of the Oroville Dam, as well as swings between weather extremes such as drought and rain. DWR started using the new data on storage capacity to inform water operation calculations on Monday.