Brannan Island State Recreation Area covers about 340 acres on the Sacramento-San Joaquin Delta, 20 miles southwest of Sacramento where Three Mile Slough meets the Sacramento River. The park’s network of sloughs, channels, and small boat ramps gives access to 700 miles of navigable Delta waterways, and the low-lying grass-and-tule landscape hosts migratory waterfowl through winter and early spring. The Delta here sits below sea level in most of the park — an engineered landscape of levees and channels since the late 1800s.

Dogs on leash are welcome at the Brannan Island campground, the picnic areas, the swim beach at Seven Mile Slough, and along the paved roads through the park. Dogs are not allowed in the interior wildlife areas or on the guided bird-watching walks. The campground sites sit just above the waterline with direct boat-launch and shoreline access.

The campground has 95 sites across two loops, most oriented toward RV-boaters launching from the adjacent ramp. The swim beach at Seven Mile Slough is protected water with a gentle entry, and dogs on leash can walk the shore during open hours. Boat rentals are seasonal from the concessionaire at the marina area.

Take Highway 160 (River Road) south from Rio Vista about 3 miles; the park entrance is well signed. Day-use admission is ten dollars per vehicle. Summer temperatures regularly exceed 95°F in the Delta; winters stay mild but fog settles in thick during December and January.