Lake Oroville Water Operations

Winter storms and spring snowmelt have filled the Lake Oroville reservoir to capacity, an increase of more than 2.5 million acre-feet of water since Dec. 1. Although the Department of Water Resources (DWR) stopped releasing water on June 17 from the main spillway, water may still be seen on the main spillway outlet as the seals on the eight radial gates are not designed to be watertight. The gate seals do not play a role in the structural integrity of the gates, which continue to operate as intended. DWR periodically maintains and adjusts the seals during low-reservoir conditions to improve their sealing capability. The radial gates were also last inspected and tested in Dec. 2022.

While water is not being released from the main spillway, water is being released from Lake Oroville through Hyatt Powerplant and the Thermalito Afterbay River Outlet. Water releases to the Feather River via these options are at 3,500 cfs, with adjustments being made as needed to ensure continued storage space in Lake Oroville for snowmelt runoff.

Lake Oroville is full and at this level there is also the potential for some waves to splash over the crest of the emergency spillway if we experience any particularly windy days. While unlikely, DWR will be monitoring for the potential of any wave runup that might splash over the crest of the emergency spillway. Wave splash will not affect the integrity of the emergency spillway structure or Oroville Dam.

Visitors to Oroville Dam may also notice minor amounts of water flowing from drains built into the emergency spillway. As the reservoir level has increased, water flow from the drains has increased, which is normal and expected with the emergency spillway design. The dam and emergency spillway continue to operate as intended.

Driftwood and other floating debris on Lake Oroville are expected due to continued water inflows from tributaries and a high lake level, in combination with past wildfires impacting the watershed. Since January, DWR and California Department of Parks and Recreation (State Parks) staff have been collecting, containing, and pulling pieces of wood out of the lake and away from boat launch ramps using boom lines. However, boaters, water skiers, and other water recreationists should take precautions when operating boats on Lake Oroville and should remain alert for floating debris.

The Lake Oroville reservoir is the largest storage facility in the State Water Project (SWP) and supports environmental and water delivery needs to 27 million Californians and reduces flood risks to downstream communities. DWR continues to closely monitor lake levels and will adjust releases accordingly to optimize operations for water storage and environmental protection while allowing for carryover storage into next year.