Cull Canyon Regional Recreation Area

Cull Canyon Regional Recreation Area (CCRRA) is a regional park located in Castro Valley, Alameda County, California. It is part of the East Bay Regional Park District (EBRPD) system.

Aquatic facilities
CCRRA includes a 1.5 acre swim lagoon and formerly included a fishing lake that resulted from damming Cull Creek. The swim area has a bathhouse, lawns, sandy beaches, and much shallow water for kids. EBRPD reports that "The [recreation area's] lagoon won the 1966 Governor's Design Award for Exceptional Distinction for Recreational Development in the category of landscape." The recreation area is open for swimming seasonally. The swim area is fenced and has a lifeguard on duty when the area is open. No dogs are allowed inside this area.

Reservoir sedimentation issue
In 2014, the San Jose Mercury-News, a local newspaper, reported that the Cull Creek Reservoir Dam would likely be drained soon because it had been judged as seismically unsafe. This hazard was caused by tons of sediment that had deposited since the dam was constructed in 1963.

By 2014, the water layer was estimated to be only 6 feet deep. The Alameda County Flood Control Manager, Hank Ackerman, said that the reservoir receives 12,000 to 20,000 cubic yards of silt and debris every year, which is trapped behind the dam. He added that the problem had reached a point where it caused a massive fish kill in August 2013, and that EBRPD had ceased to restock the reservoir with fish.

A temporary solution to the seismic concern was obtained in 2006 when engineers penetrated the concrete spillway with 12-inch pipe that relieved pressure on the dam by lowering the water level in the lake. Ackerman noted that dredging the lake to remove the sediment had been estimated to cost $16 million and require 28,000 round trips with double bottom dump semitrailers to remove the estimated 450,000 cubic yards of sediment. The dam would need to be reinforced after the silt is removed.

Almeda County engineers have proposed to notch the reservoir's weir. This would let water flow downstream,leaving the accumulated sediment behind. Ackerman said that cost would be less than $1 million, and that the seismic threat would be eliminated because the (California) Division of Safety of Dams would no longer consider it a dam if it didn't hold back water.”

Hiking
The Chabot-to-Garin Regional Trail (part of the Bay Area Ridge Trail) runs along the east side of the Cull Canyon reservoir. The trail then leads north through property owned by the East Bay Municipal Utility District (EBMUD) for 6 miles to EBMUD's Chabot staging area on Redwood Road. The Willow View Trail leads from this point into Anthony Chabot Regional Park.