Lake guide
San Luis Reservoir
Gustine, Merced County, CA
Overview
San Luis Reservoir is a huge off-stream reservoir in the western San Joaquin Valley, on the east side of Pacheco Pass about 12 miles west of Los Banos. State Route 152 runs along its north shore. Completed in 1967, it holds about 2,041,000 acre-feet over roughly 12,700 acres, with about 65 miles of shoreline. State Parks, DWR and the Bureau of Reclamation jointly run San Luis Reservoir State Recreation Area, which also includes O'Neill Forebay and Los Banos Creek Reservoir.
Launching and layout
The main reservoir has two launch ramps, Dinosaur Point on the west side and Basalt on the south side. O'Neill Forebay, the smaller lake just below the dam, is reached from Donohugh Road and Gonzaga Road and has the Medeiros ramp.
Wind is the main hazard
The reservoir is known for strong winds. Wind warning lights stand at the Basalt entrance station, Quien Sabe Point and the Romero Visitor Center, and at the Medeiros ramp and South Beach on O'Neill Forebay. A flashing yellow light means caution; red means winds over about 30 mph and the lake is closed.
Golden mussels and exit inspections
Golden mussels have been found in O'Neill Forebay, and in October 2025 the state announced their detection in San Luis Reservoir itself. Since October 29, 2024, every boat leaving San Luis Reservoir, O'Neill Forebay or Los Banos Creek Reservoir must be inspected by State Parks staff. Boats leaving these lakes can't launch in another San Luis SRA lake until a seven-day dry-out has been observed, and they won't get a "clean boat" tag. Expect other lakes to ask where you last launched.
Getting there & access
By road
State Route 152 crosses Pacheco Pass and runs along the north shore. Dinosaur Point Road leads to the Dinosaur Point ramp on the west side. The Basalt area and the SRA's mailing address are on Gonzaga Road in Gustine. O'Neill Forebay is reached from Donohugh Road and Gonzaga Road, and Los Banos Creek Reservoir from Canyon Road off I-5.
Leaving the lake: exit inspection
Before you leave, State Parks staff inspect your boat to make sure all water is drained from outboards, bilges, live-wells and anywhere else water collects. Pull the plugs and drain everything before you get in line.
Wind warning lights
Check the lights at the Basalt entrance station, Quien Sabe Point and the Romero Visitor Center (main reservoir), and at the Medeiros ramp and South Beach (O'Neill Forebay). Yellow means caution for winds of roughly 15–30 mph; red means winds over 30 mph and the lake is closed, so get off the water.
Moving to another lake
A boat leaving San Luis Reservoir, O'Neill Forebay or Los Banos Creek Reservoir can't launch in another San Luis SRA lake until a seven-day dry-out has passed. Other operators set their own dry-time rules, so check with your next lake before you go.
Amenities
- Dinosaur Point ramp — West side of the main reservoir, off Dinosaur Point Road
- Basalt ramp — South side of the main reservoir, near the Basalt Campground
- O'Neill Forebay launch — Medeiros ramp; the forebay facility lists about 250 car-and-trailer spaces
- Campgrounds — Basalt, San Luis Creek, Medeiros and Los Banos Creek (check current status; Basalt has been listed as temporarily closed)
- Fish cleaning and showers — Listed at the O'Neill Forebay facility, along with restrooms and a swim area
- Visitor center — Romero Overlook Visitor Center above the reservoir
Rules & official resources
- As of October 29, 2024, boats leaving San Luis Reservoir, O'Neill Forebay and Los Banos Creek Reservoir must be inspected by California State Parks staff to make sure all water is drained
- Boats leaving San Luis Reservoir, O'Neill Forebay and Los Banos Creek Reservoir may not launch in another San Luis SRA lake until a seven-day dry-out period has been observed
- A "clean boat" tag will not be granted to boats leaving San Luis SRA lakes
- Obey the wind warning lights: red means winds over 30 mph and the lake is closed
- Motorized vessels used in fresh water must display the California Mussel Fee sticker, one on each side of the hull next to the registration sticker; paying the fee doesn't exempt a boat from local inspections or inspection fees
- California Boater Card required for all operators of motorized vessels, regardless of age, since January 1, 2025
Common boat service needs here
Drain-and-dry and wash service
Exit inspections check that every drop of water is gone from outboards, bilges and live-wells. Owners who trailer between lakes rely on thorough wash, drain and dry-out service so the boat clears quarantine or inspection at the next lake.
Find Boat Detailing & Washing providers →Engine and cooling-system service
Golden mussels clog cooling passages and intakes. Boats used here benefit from regular checks of raw-water intakes, impellers and outboard cooling systems.
Find Marine Mechanics & Engine Service providers →Wind-damage repairs
Steep, wind-driven waves can bang boats against docks and shorelines when wind comes up quickly. Gelcoat and fiberglass repair after a rough day is a common need.
Find Fiberglass, Gelcoat & Structural Repair providers →Covers and canvas
Hot, windy valley summers are hard on Bimini tops, covers and upholstery. Tight-fitting covers that hold up to high wind are worth the investment.
Find Canvas, Covers & Upholstery providers →Guides & FAQs
Nearby providers
No providers listed near this location yet — check back soon.
Sources
Last verified October 6, 2026