Mokelumne River

The Old River is a tidal distributary of the San Joaquin River that flows for about 40 miles (64 km) through the Sacramento–San Joaquin River Delta in Northern California. The Old River was once the main channel of the San Joaquin until navigation (Stockton Deepwater Shipping Channel) and flood control projects in the late 19th and 20th century fixed the San Joaquin to its present course past Stockton. It diverges from the San Joaquin near Tracy, about 38 miles (61 km) upstream from Antioch, and first runs west towards Mountain House, then north to rejoin the San Joaquin 13 miles (21 km) above Antioch. The river is lined with levees that prevent flooding of the adjacent Delta islands, many of which lie below sea level. The Middle River runs east of and roughly parallel to Old River. False River diverges from Old River about a mile (1.6 km) above the Old River's mouth and runs westward to join the San Joaquin at a point closer to Antioch. Part of the Old River forms the boundary between San Joaquin County on the east and Contra Costa County to the west. About halfway along its course the Old River passes by the Clifton Court Forebay, where water is pumped from the Delta to support California's two primary water supply systems, the Central Valley Project and State Water Project. Because both projects derive their sources from the Sacramento River further north, pumping results in a reverse flow in the Old River as water flowing through the Delta Cross Channel is drawn southward through the Delta and up the Old River. (Naturally, the Old River would have flowed in a northerly direction). During dry summers, this often results in saltwater intrusion from San Francisco Bay. The reverse flow also confuses migrating salmon in the San Joaquin River which may have contributed to the decline of the species in the 20th century. Since the 1960s, the California Department of Water Resources has maintained temporary barrier dams to control the flow of water, a system which has improved water quality and circulation. The Head of Old River barrier is routinely installed during spring at the point where the Old River diverges from the San Joaquin, in order to prevent outmigrating young salmon from entering the longer, winding Old River where they are less likely to survive the journey to the sea. A pumping station on Old River east of Discovery Bay provides fresh water to Los Vaqueros Reservoir via pipeline. The Peripheral Canal project, proposed since the 1960s would have bypassed diverted water flows around the Delta and eliminated the reverse flow in the Old River. However, the canal was never built due to environmental concerns for the Delta region. On the right bank, the Old River borders Berts Island, Union Island, Victoria Island, Woodward Island, Bacon Island, and Mandeville Island. On the left it borders Stewart Tract, Coney Island, Widdows Island, Byron Tract, Orwood Tract, Palm Tract, Holland Tract, Little Mandeville Island, Quimby Island, and Webb Tract. The Old River also skirts the Franks Tract State Recreation Area, a former Delta island that is now submerged and forms a lake. The Old River ranges from 5 to 10 feet (1.5 to 3.0 m) deep and from 150 to 1,600 feet (46 to 488 m) wide. The U.S. Geological Survey operates five stream gauges on the Old River. Measured at Bacon Island, the Old River had an average reverse flow of 1,823.6 cubic feet per second (51.64 m3/s) between 2006 and 2014.

Bouldin Island is an island in the Sacramento-San Joaquin River Delta, 20 kilometers (12 mi) northwest of Stockton on the Stockton Deepwater Shipping Channel. It is in San Joaquin County, and managed by Reclamation District 756. The island is owned by the Metropolitan Water District of Southern California.

Venice Island is an island in the Sacramento-San Joaquin River Delta, fifteen kilometres (9.3 miles) northwest of Stockton. It is in San Joaquin County, California, and managed by Reclamation District 2023. It is owned by Barron Hilton and the DiNapoli family. The 3,100-acre (1,300 ha) island is bounded on the north- and northeast by Potato Slough, on the southeast by Little Connection Slough, on the south by the Stockton Deepwater Channel Venice Cut, and on the west by the San Joaquin River-Stockton Deepwater Shipping Channel.

This list of islands of California is organized into sections, generally arranged from north to south. The islands within each section are listed in alphabetical order. The Geographic Names Information System (GNIS) lists 527 named islands in the state.

Mandeville Island is an island in the Sacramento–San Joaquin Delta located about 15 miles (24 km) northwest of Stockton, in central California in the United States. The island covers about 5,500 acres (2,200 ha), and lies between the Old River to the west and Middle River to the east, both distributaries of the San Joaquin River-Stockton Deepwater Shipping Channel. The Connection Slough forms the island's southern end, and Sand Mound Slough borders the island to the north. The island lies directly to the east of Franks Tract State Recreation Area. It is in San Joaquin County, and managed by Reclamation District 2027.

Quimby Island is a small island in the Sacramento–San Joaquin River Delta, whose coordinates are 38.0251993°N 121.5713413°W / 38.0251993; -121.5713413 (Quimby Island). It is in Contra Costa County, and managed by Reclamation District 2090.

The United States Coast Guard Cutter Fir (WAGL/WLM 212) was the last lighthouse tender built specifically for the United States Lighthouse Service to resupply lighthouses and lightships, and to service buoys. Fir was built by the Moore Drydock Company in Oakland, California in 1939. On 22 March 1939, the U.S. Lighthouse Tender Fir was launched. She was steam driven with twin screws, 175 feet (53 m) in length, had a beam of 32 feet (9.8 m), drew 11 feet 3 inches (3.43 m) of water, and displaced 885 tons. Fir was fitted with a reinforced bow and stern, and an ice-belt at her water-line for icebreaking. She was built with classic lines and her spaces were lavishly appointed with mahogany, teak, and brass. The crew did intricate ropework throughout the ship. The cost to build Fir was approximately US$390,000. Fir's homeport was Seattle, Washington for all but one of her fifty one years of service when she was temporarily assigned to Long Beach, California when USCGC Walnut was decommissioned on 1 July 1982. On 1 July 1939 the United States Lighthouse Service became a part of the United States Coast Guard. On 1 October 1940 Fir was commissioned as the United States Coast Guard Cutter Fir (WAGL-212). With the onset of World War II Fir was assigned to the U.S. Department of the Navy and painted battleship grey. The following armament was installed for war service: M2 Browning machine guns, a 3-inch gun, and depth charges. Her wartime duties included picket duty, towing gunnery targets, and patrolling the Washington and Oregon coasts. In 1965, Fir was reclassified as a USCG coastal buoy tender (WLM). On 27 May 1988, after the decommissioning of USCGC Ingham, Fir gained the distinction as the U.S. Coast Guard's oldest commissioned cutter. In accordance with a Coast Guard custom, she displayed gold hull numbers on her bow and was designated as "Queen of the Fleet" on 30 May 1988. On 1 October 1990, the 200th anniversary year of the U.S. Coast Guard, Fir was honored again with the celebration on her 50th birthday. One year later, on 1 October 1991 Fir was decommissioned, and; on 27 April 1992 was designated a National Historic Landmark by the United States Secretary of the Interior. During her career, Fir was a multi-mission ship whose accomplishments mirrored the changing American maritime scene, and the needs of the U.S. Coast Guard for more than half a century. Fir's primary duties included resupplying coal, potable water, food, and other vital provisions; icebreaking, aids to navigation (ATON) maintenance, delivery and pick-up of U.S. Mail for lightships and lighthouses on the Washington and Oregon coasts. Fir tended the lightships at Umatilla Reef off La Push, Washington and Swiftsure Bank at the entrance of the Strait of Juan de Fuca Washington. In addition to servicing aids to navigation (ATON), Fir stood war duties during World War II, performed search and rescue missions, marine environmental protection, and law enforcement. For her last project, Fir was tasked to do what she was originally built for in 1939. In July 1991, Fir renovated and restored the Cape Flattery Lighthouse on Tatoosh Island at the entrance to the Strait of Juan de Fuca. There is successor cutter also named Fir, USCGC Fir (WLB-213), currently in active use by the Coast Guard, which is a 225-foot (69 m) cutter. She was launched in 2003 and is based in Astoria, Oregon.

Terminous is a census-designated place in San Joaquin County, California. Terminous sits at an elevation of 7 feet (2.1 m) below sea level. It is located on the Terminous Tract, an island of the Sacramento–San Joaquin River Delta. The 2010 United States census reported Terminous's population as 381. Terminous was named from its location at the "terminus" of a road.

Little Venice Island is a small island in the Sacramento–San Joaquin River Delta. It is part of San Joaquin County, California. Its coordinates are 38°03′02″N 121°30′05″W, and the United States Geological Survey measured its elevation as 0 ft (0 m) in 1981. It appears on a 1952 USGS map of the area.

Franks Tract State Recreation Area (SRA) is a state park unit of California, United States, featuring a flooded area in the Sacramento–San Joaquin River Delta. It is accessible only by water. Franks Tract, and a smaller adjoining submerged property called "Little Franks Tract", are situated between the False River and Bethel Island. The recreation area is used primarily for fishing and waterfowl hunting, because of its exposure to frequent strong winds and fluctuating water levels. In times of high water, the entire site can be submerged except for portions of the old levees. The 3,523-acre (1,426 ha) park was established in 1959. It is managed from nearby Brannan Island State Recreation Area, 6 miles (9.7 km) to the northwest.

Medford Island is a small island in the San Joaquin River delta, in California. It is part of San Joaquin County, and managed by Reclamation District 2041. Its coordinates are 38.0371435°N 121.5113407°W / 38.0371435; -121.5113407 (Medford Island).

Little Mandeville Island is a small, mostly submerged island in the San Joaquin River delta, in California. It is part of San Joaquin County, and its coordinates are 38.0104776°N 121.5649522°W / 38.0104776; -121.5649522 (Little Mandeville Island). In 1994, 376 acres (152 ha) of former farmland was inundated with water after a levee broke.