O'Neill Forebay is a 2,250-acre reservoir located in California's San Joaquin Valley, about 10 miles west of Los Banos. With 14 miles of shoreline, it offers diverse paddling opportunities. The only boat ramp is at the San Luis Creek area. All boat traffic must move counterclockwise around marker buoys in the lake's center.

Paddlers should be aware of several hazards. Extreme shallow areas exist along the entire southern shoreline, Catfish Flats, and Mud Flats. The lake is susceptible to sudden changes in wind and weather. Wind warning lights near the old Medeiros boat ramp and above South Beach alert paddlers to dangerous conditions.

Boating hours are from 6 a.m. until sunset, with all watercraft required to be off the lake by sundown. Speed restrictions apply in certain areas, and boats are prohibited at North Beach. A 5 mph speed limit is enforced on nearby Los Banos Creek Reservoir.

The forebay is known for excellent fishing, particularly for striped bass. Five world record or former world record striped bass have been caught here. Other species include largemouth bass, crappie, and catfish.

Facilities include campgrounds, picnic areas, and hiking trails. The San Luis Creek Accessible Trail offers a 5-mile route along the shoreline. Guided kayak tours led by park staff are available in summer.

Paddlers must comply with a mussel prevention program to protect against invasive species. The lake serves as a major family destination for the west central valley, offering additional activities like swimming and windsurfing.

Water levels can fluctuate significantly, so paddlers should check current conditions before visiting. The surrounding landscape features subalpine flora and steep canyon walls, providing a scenic backdrop for paddling adventures.