Lake Oroville Update - June 28, 2024

Published: June 28, 2024

Using Advanced Lasers and Sonar to Determine Lake Oroville's Storage Capacity

With California experiencing extreme swings between severe drought and torrential rain, the Department of Water Resources (DWR) wanted to see if the State Water Project's largest reservoir, Lake Oroville, had shrunk (or lost storage capacity) due to weather swings and almost six decades of service. DWR utilized the latest terrain-mapping technology to determine if there have been any changes in the lake's volume to optimize how the reservoir is operated and ensure accuracy in estimating California's water supply availability.

Lake Oroville was created in the 1960s with the construction of Oroville Dam. When Lake Oroville was filled in 1968, surveys estimated the dam impounded 3,537,577 acre-feet of water with a maximum depth of 690 feet and 167 miles of shoreline spread across the main reservoir and its three connecting Feather River forks.

Because decades have passed since its construction, DWR sought to assess whether sedimentation (rock and silt settling on the lakebed floor) had altered Lake Oroville's storage capacity and topography significantly. Starting with an airplane-mounted LiDAR (Light Detection and Ranging) laser system, DWR took advantage of the lake's historically low water levels in 2021 to first map portions of the basin that would typically be under water during normal years. Then a boat outfitted with multibeam-sonar bathymetry instruments spent weeks in 2022 sending sonar pulses into the depths of Lake Oroville to map its underwater surface terrain. What resulted were highly detailed 3D topographic terrain models of the bottom of the lake, which DWR engineers used to calculate a new storage capacity of 3,424,753 acre-feet, approximately 3 percent less than previously estimated.

"Having updated storage capacity data allows us to operate Lake Oroville in a more efficient manner," said John Yarbrough, DWR's deputy director of the State Water Project. "It ensures we are providing adequate flood storage protection during winter months and accurately accounts for the state's water supply, which is especially important as we experience climate change-driven weather extremes."

Read more about DWR's project to update Lake Oroville's storage capacity on our blog.

Note: DWR will start using Lake Oroville's new storage capacity data for water operation calculations on Monday, July 1, 2024.

Fourth of July in Oroville

Celebrate our nation's independence on July 4 with a spectacular fireworks show at the North Thermalito Forebay Recreation Area located off Garden Drive in Oroville. This year's display starts 30 minutes after sunset and has two primary viewing locations: North Thermalito Forebay and the Nelson Sports Complex.

The North Thermalito Forebay Recreation Area opens at 8 a.m. with an $8 entrance fee. Popular for sailing and paddle sports, the North Thermalito Forebay day use area hosts non-motorized boating with a swim beach, a large picnic area with barbecue grills, and abundant shade trees. This area also has restroom facilities and drinking fountains. Open for Independence Day festivities, the Forebay Aquatic Center offers a wide range of rental equipment, from kayaks and canoes, to hydrobikes and pedal boats, which can be rented by the hour or day. North Forebay visitors are required to be off the water by sunset.

The Nelson Sports Complex opens at 4:30 p.m. to reserve a prime spot for fireworks viewing. There is no entrance fee at this facility with festivities including food trucks, music, and vendors. Visitors are encouraged to bring coolers, picnic baskets, blankets, or lawn chairs. However, alcohol, glass containers, and pets are not permitted during Fourth of July celebrations.

DWR and the Department of Parks and Recreation (State Parks) provide resources and support for this City of Oroville/Oroville Chamber of Commerce event. More information about July 4 fireworks can be found at visitoroville.com.

Oroville Recreation

DWR, State Parks, and CDFW maintain over 92 miles of trails in the Oroville area. An interactive map of recreation facilities, including open trails and their permitted uses (hike, bike, horse, multi), is available on DWR's Lake Oroville Recreation webpage. A paper trail map is available at various locations, including most entrance kiosks and the Lake Oroville Visitor Center.

Staffed by knowledgeable guides, the Visitor Center features interpretive displays on Oroville Dam, area geology, wildlife and habitat, hydroelectric power, and cultural and historical artifacts. View videos in the theater about the construction of Oroville Dam, walk or hike along nearby trails, and visit the 47-foot-tall observation tower that provides unsurpassed panoramic views of surrounding areas. Free guided tours for school and community groups are available by reservation. Parking and admission to the Visitor Center are free.

Lake Oroville is one of the State Water Project's premier recreational destinations and one of California's best fishing spots. The lake provides both warm-water and cold-water fisheries and is a popular destination for bass tournaments. The marinas at Bidwell Canyon and Lime Saddle are open daily and provide a variety of services including a convenience store, gas, and boat rentals. Below the Oroville Dam, the Thermalito Afterbay and the Feather River offer additional excellent fishing opportunities.

Upstream migrating fish totals through the Feather River Fish Monitoring Station between January 1 and June 13 are:

• Spring-run Chinook salmon: 5,776
• Steelhead: 876
• Due to higher flows in the low-flow channel of the Feather River between February 26 and March 18, some fish swam over the monitoring station and were not counted in upstream migration totals.

Current Lake Operations

Lake Oroville is at 891 feet elevation and storage is approximately 3.4 million acre-feet (MAF), which is 96 percent of its total capacity and 126 percent of the historical average.

Feather River flows are at 1,500 cfs through the City of Oroville with 4,250 cfs being released from the Thermalito Afterbay River Outlet (Outlet) for a total Feather River release of 5,750 cfs downstream. On Sunday, June 30 total Feather River flows will be increased to 8,000 cfs with Outlet releases increased to 6,500 cfs. DWR continues to assess Feather River releases daily.

Releases from Oroville Dam's main spillway ceased in May, but water is still being released through the Hyatt Powerplant for power generation, water deliveries, and environmental requirements. When the main spillway is not in use, 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. Visitors to Oroville Dam may also notice minor amounts of water flowing from drains built into the emergency spillway. This is normal and expected given the emergency spillway design. The dam and emergency spillway continue to operate as intended.

The public can track precipitation, snow, reservoir levels and more at the California Data Exchange Center. The Lake Oroville gage station is identified as "ORO."

All data as of midnight 6/27/2024.