Don Castro Regional Recreation Area

Don Castro is a compact 101-acre park on the boundary between Hayward and Castro Valley, built around a swim lagoon created in 1964 when the Alameda County Flood Control and Water Conservation District dammed San Lorenzo Creek. The lagoon is filled with filtered, chlorinated EBMUD water and has a large roped-off shallow area for children; it is scheduled to reopen for the 2027 swim season. Only ADA-trained service dogs are allowed in the swim area. The neighboring San Lorenzo Creek Reservoir is closed to boating, swimming, and any body contact, including dogs.

Anglers 16 and older need a state fishing license, but no District permit. Trails connect to the Bay Area Ridge Trail, the Chabot-to-Garin Trail, and more than five miles of paths in Five Canyons Open Space. First-come picnic sites and reservable group areas sit outside the swim complex.

The park has wheelchair-accessible restrooms, drinking water, and disabled parking, and free beach wheelchairs can be arranged through the park office; staff bring the chair to the beach and show how it works. Parking is $5 per vehicle on weekends and holidays from June through September, with no fee collected October through May.