DWR starting maintenance work on Oroville Dam spillway

Appeal-Democrat, Marysville, Calif.
·2 min read

Sep. 11—Officials with the Department of Water Resources (DWR) said maintenance work on Oroville Dam's main spillway was expected to start this week as construction staging equipment and materials make their way to the worksite.

Maintenance work is expected to be performed on localized sections of the spillway to address areas of deteriorated concrete and sealant identified during annual inspections, DWR officials said.

"Periodic concrete and sealant repairs of the spillway are expected due to seasonal temperature variations, spillway releases, and sun exposure," officials said. "Approximately 500 square-feet of total concrete repairs are anticipated, representing less than 0.1% of the spillway's surface. Concrete work by contractor Syblon Reid will include tying new concrete material to the spillway's first layer of reinforcing steel to provide a longer-lasting repair."

Other planned work includes the replacement of a "joint sealant at select chute slab and wall joints that degrade over time due to the spillway's environment." Officials also will inspect 51,000 feet of piping that supports the spillway's drainage system.

"In 2023 alone, Oroville Dam's main spillway has passed over 2,370,000 acre-feet of water — approximately 67% of the capacity of Lake Oroville," officials said. "The main spillway has continued to perform and operate as designed, passing flows up to 36,000 cubic feet per second this spring. Construction work represents anticipated maintenance activities considering the time since completion of construction, the spillway's use, and its environment."

DWR officials said the identified work is expected to continue through Nov. 15, depending on weather conditions and Oroville Dam operations.

"DWR will be monitoring reservoir levels and weather forecasts closely and will complete repair work early if spillway releases are required for flood control management," officials said. "The construction contract period extends through 2025, permitting the contractor to complete repairs in future dry seasons should the 2023 construction window be limited."