Harbor guide
Sacramento-San Joaquin Delta
Bethel Island, Contra Costa County, CA
Overview
The Sacramento-San Joaquin Delta is the inland boating hub of Northern California, a maze of rivers, sloughs and flooded islands spread across six counties: Contra Costa, Sacramento, San Joaquin, Solano, Yolo and Alameda. State Parks describes it as more than 1,000 miles of navigable waterways. Five rivers feed it, the Sacramento, San Joaquin, Mokelumne, Cosumnes and Calaveras, and about 1,330 miles of levees hold the islands in place. Boaters use it for bass and striped bass fishing, waterskiing, wakeboarding, houseboating, sailing and quiet slough cruising.
Layout
The Sacramento River runs down the west side past Rio Vista, and the San Joaquin River comes up from Stockton on the south. They meet near Antioch and Pittsburg on the way to Suisun Bay. In between are the central Delta sloughs, Franks Tract, Bethel Island and the residential waterways of Discovery Bay. Marinas, resorts and public ramps cluster in these areas. The Delta's top-end channels are wide and carry ship traffic, while the back sloughs are narrow, shallow and lined with levees.
Tides, current and weather
This is fresh water, but it is tidal. The USGS reports that flow reverses twice a day as far upstream as Freeport, and water can move faster than 2 mph, carrying a parcel of water 8 to 9 miles downstream toward Rio Vista over one 6-hour ebb. Plan your passage times around the current and expect wind to build in open stretches like Franks Tract.
What is different about boating here
Most of the Delta's hazards are things you can't see: shallows at channel margins, submerged levee remnants, logs, abandoned vessels and out-of-service pipes. In May 2026 San Joaquin County deputies warned about a submerged pipe near Mildred Island's south entrance. Aquatic weeds, mainly water hyacinth and Brazilian waterweed (Egeria densa), foul props and intakes, and State Parks runs a herbicide control program each season. Golden mussels were found at the Port of Stockton in October 2024, so clean, drain and dry your boat after every outing. Drawbridges cross the main channels, and heavy summer weekend traffic means wakes in narrow sloughs are a constant source of complaints.
Getting there & access
Entering from the bay
Most boats from San Francisco Bay enter the Delta by way of Suisun Bay and the Antioch and Pittsburg area, then head up the San Joaquin or Sacramento River. Large commercial vessels use the deep-water channels, so keep clear of ships and tugs and expect them to have limited room to maneuver.
Hidden hazards
Stay in marked channels where you can. Shallows at the margins, submerged levee remnants, logs, abandoned boats and old pipes are common. San Joaquin County deputies warned in May 2026 about a PG&E pipe near the south entrance to Mildred Island that sits about 2 feet below the surface at low tide. Slow down when you see red hazard buoys.
Drawbridges
Several channels are crossed by Caltrans and county drawbridges that open for vessels under federal rules. On the Sacramento River, 33 CFR 117.189 sets regular opening hours for bridges from Isleton upriver (May 1 to October 31, 6 a.m. to 10 p.m.; November 1 to April 30, 9 a.m. to 5 p.m.). At other times at least four hours of notice goes to the drawtender at the Rio Vista Bridge. Other bridges have their own rules in the same regulation. VHF channels and phone numbers for individual bridges are not listed in the official text we reviewed, so confirm them in the current Coast Pilot or with the bridge before you rely on a particular opening.
Public ramps
Public launch facilities include Brannan Island State Recreation Area near Rio Vista, the City of Rio Vista launch behind City Hall, the Antioch Marina ramp, and many private marina ramps at Bethel Island, Discovery Bay and Oakley. Check with each operator for hours and fees, and for low-water conditions.
By land
State Route 12 crosses the Sacramento River at Rio Vista over the Rio Vista Bridge. State Route 160 leads to Brannan Island, and State Route 4 serves Antioch, Discovery Bay and Bethel Island.
Amenities
- State recreation area — Brannan Island SRA near Rio Vista: 10-lane launch ramp, camping, picnic areas and swimming beaches
- Municipal launch, Rio Vista — Two-lane ramp and dock behind City Hall at the end of Front Street
- Municipal marina, Antioch — City-run marina with launch ramps on the San Joaquin River
- Bethel Island marinas — More than a dozen marinas and resorts; State Parks lists about two dozen boating facilities on the island
- Fuel — Examples: Delta Marina Yacht Harbor (Rio Vista) lists 24-hour gas, with diesel and propane in store hours; Sugar Barge Marina (Bethel Island) lists a 24-hour fuel dock
- Pump-outs — Pump-outs have been listed at marinas in Rio Vista, Brannan Island, Discovery Bay, Bethel Island and Antioch; call ahead because station availability changes
- Guest berthing — Delta Marina in Rio Vista has about 800 feet of guest dock, with reservations through Dockwa
- Dry storage and boat service — Marinas such as Discovery Bay Marina and Sugar Barge offer dry storage; SierraWest Boatworks works on site at Delta Marina
- Sheriff marine patrols — Contra Costa and San Joaquin sheriff marine units patrol their sections of the Delta
Rules & official resources
- California Boater Card required for all operators of motorized vessels, regardless of age, since January 1, 2025
- 5 mph maximum within 100 feet of bathers, and within 200 feet of a swimming beach, swim float, or dock or launch float with boats moored or in use
- Vessels under 26 feet with an engine must have an engine cut-off switch, and the operator must wear the lanyard when above 5 mph
- One wearable life jacket per person aboard; children under 13 must wear one on vessels 26 feet or less while underway
- Drawbridges on the Sacramento River open on signal during posted seasonal hours; outside those hours at least four hours of notice goes to the Rio Vista Bridge drawtender
- Untreated sewage may not be discharged in the navigable waters of the Delta; use a pump-out station
- Clean, drain and dry your boat, trailer and gear after every outing; golden mussels were found in the Delta in October 2024
- Report golden mussel sightings to CDFW at invasives@wildlife.ca.gov or (866) 440-9530
Common boat service needs here
Weed-fouled props and intakes
Water hyacinth and Brazilian waterweed wrap around props and clog raw-water intakes. Mechanics are often called to clear cooling systems and replace damaged impellers after trips through weedy sloughs.
Find Marine Mechanics & Engine Service providers →Hull cleaning and bottom care
Boats kept in warm Delta water for months pick up growth on the bottom and running gear. Many slip holders keep a diver on a regular schedule and haul out for fresh bottom paint.
Find Bottom Cleaning, Hull Cleaning & Dive Services providers →Gelcoat and sun damage
Long hot, dry summers oxidize gelcoat and chalk the finish. Compounding, polishing and wax are a standard annual job.
Find Gelcoat, Oxidation & Paint Correction providers →Canvas and upholstery
Delta sun and heat wear out Bimini tops, enclosures and cushions. Houseboat and cruiser owners often replace covers and vinyl each few seasons.
Find Canvas, Covers & Upholstery providers →Hull and structural repair
Shallows, logs and submerged levee remnants cause prop, skeg and hull strikes. Fiberglass shops handle grounding repairs.
Find Fiberglass, Gelcoat & Structural Repair providers →Guides & FAQs
Nearby providers
No providers listed near this location yet — check back soon.
Sources
- parks.ca.gov
- pubs.usgs.gov
- parks.ca.gov
- ecfr.gov
- dbw.parks.ca.gov
- sjsheriff.org
- contracosta.news
- wildlife.ca.gov
Last verified October 2, 2026