San Joaquin River

San Joaquin River
Map of the San Joaquin River watershed
Map of the San Joaquin River watershed
Origin Martha Lake (California)
Mouth Sacramento-San Joaquin Delta
Basin countries United States (100%)
Length 330 mi (530 km)
Source elevation 11,004 ft (3,354 m)
Basin area 32,000 sq mi (83,000 km2)

The San Joaquin River (pronounced /ˈsæn wɑːˈkiːn/), 330 miles (530 km) long, is the second-longest river in California, United States. The average unimpaired runoff of the main stem of the river at Millerton Reservoir is about 1.8 million acre feet per year (2.2 km³).[1] The San Joaquin and its eight major tributaries drain about 32,000 square miles (83,000 km²) of California's San Joaquin Valley. Water from the river is used to irrigate 1,500 square miles (3,900 km²) of highly productive farmland on the east side of the Central Valley where 200 kinds of produce are raised from oranges to cotton.

It originates high on the western slopes of the Sierra Nevada and drains most of the area from the southern border of Yosemite, south to Kings Canyon National Park, making it the second largest river drainage in the state. The San Joaquin River's tributaries include the Stanislaus River, Tuolumne River, Merced River, Calaveras River and Mokelumne River.

Contents

Geography / course

Headwaters

The river originates at three locations. The South Fork begins at Martha Lake () at an elevation of 11,004 feet (3354 m). The Middle Fork begins at Thousand Island Lake and joins the South Fork north of Balloon Dome in the Ansel Adams Wilderness. The North Fork begins at an unnamed lake at that is at 3410 m (11190 ft) elevation and joins the Middle Fork east of Junction Butte at .

The confluence passes through a narrow valley of which John Muir once said: "Certainly this Joaquin Canyon is the most remarkable in many ways of all I have entered." It eventually emerges from the foothills at what was once the town of Millerton, the location of Friant Dam since 1944, which forms Millerton Lake.

Tributaries / canals / lakes

The river flows west to the Central Valley, where it is joined by the Sierra's other great rivers and then at Mendota Pool flows north to the Sacramento-San Joaquin Delta and then San Francisco Bay. With the exception of overflow and drain water along the North Fork of the Kings River, which meets the San Joaquin River at Mendota Pool, the San Joaquin River itself is the southern most river of the greater San Joaquin River watershed.

During some years, portions of the San Joaquin River (and some of its tributaries) will run dry as water is diverted from the river for urban or agricultural use. Though the agricultural drain water or urban waste water will be returned to the original channel downstream of the point of diversion, the water returned to the river is not of the same quality as the water found in the upper watersheds. In other places, such as at the confluence of the San Joaquin and Chowchilla Rivers near Dos Palos, California, the entire river has been diverted to man-made bypass channels, such as the Eastside Bypass. These bypass channels were originally designed to provide additional flood protection for local land owners. However, the levees on these bypass channels tended to be better designed and thus the main channel of the San Joaquin runs dry in some of these places.

San Joaquin River at Mendota Pool flood control gates during high flows of April 2006.
Original channel of San Joaquin River north of Dos Palos, California near confluence of San Joaquin and Chowchilla Rivers and diversion of the San Joaquin River to the Eastside Bypass (April 2006).

The following rivers are tributaries to the San Joaquin River:

The following lakes and reservoirs are on the San Joaquin River watershed:

The following artificial canals are part of the San Joaquin River system:

Confluence / destination

Fish Protection Barrier at the Head of the Old River along lower San Joaquin River.

The San Joaquin River meets the Sacramento River near the city of Antioch. Together they form the Sacramento-San Joaquin Delta, one of the largest estuaries in the United States. Before meeting the Sacramento River, the San Joaquin River has two distributary rivers, the Old River and the Middle River, both of which once were the main channels of the river. Due to the bend in the San Joaquin River channel at the head of the Old River, a significant portion of the San Joaquin River flow continues down the Old River instead of heading northward along the San Joaquin. This flow split causes problems for outmigrating salmon, as the flows along the Old River are eventually divided between the Old River, Middle River, and Grant Line Canal. Lower flows in these channels place the salmon in danger of predation and entrainment via agricultural diversions and urban drinking water exports. In response to this problem, the California Department of Water Resources and California Department of Fish and Game construct and manage temporary rock barriers at the head of the Old River in order to keep fish in the main channel of the San Joaquin River.

Physical characteristics

Ecology

Prior to human development in the San Joaquin Valley that began in the 1850s, the San Joaquin River and its tributaries tended to flood the valley in the winter months. These seasonal wetlands became habitat for the migratory birds of the Pacific Flyway. Today environmental mitigation projects, such as the San Luis National Wildlife Refuge, have been established to recreate the seasonal wetland habitats used by these birds and many other native species.

Historically, the native habitat of the endangered San Joaquin Kit Fox and riparian brush rabbit included the riparian zone near the San Joaquin River.

Prior to the completion of Friant Dam in 1942, the San Joaquin River had the southern most habitat for salmon in the United States. However, the diversion of water from the upper reaches of the San Joaquin River and its tributaries significantly reduced the number of Chinook Salmon native to the river.

Economics

Navigation

Sedimentation has greatly reduced the San Joaquin River system's navigability. The Stockton Deep Water Ship Channel (DWSC) makes the lower reach of the river navigable for ocean freighters as far inland as Stockton, but maintaining the channel requires extensive dredging. The abrupt geometry change from the shallow river channel upstream of Stockton to the deep Ship Channel itself is believed to contribute to the low dissolved oxygen concentrations in the river near the DWSC.[2]

Historical / political events

Since the mid-19th century, the waters of the San Joaquin have been developed and diverted for human use. It produces hydroelectricity for export to the Bay Area, provides water for irrigation for some of California's most productive farmlands, and provides the sole source of drinking water supply to a number of rural towns in California's Central Valley.

The operations of Friant Dam have been controversial in recent years. Friant Dam was included in California's State Water Plan, which was approved by the voters of California in 1933. During the Depression, California could not finance the construction of the State Water Plan features, and it turned to the federal government for help. Friant Dam was constructed as part of the federal Bureau of Reclamation's Central Valley Project in the 1940s. Its purpose was to divert the waters of the San Joaquin to maximize their use to help people, both to irrigate crops and to provide groundwater recharge. As contemplated by the Central Valley Project Act, most of the waters of the San Joaquin River are diverted into canals so that the river remains dry for a 17 mile (27 km) stretch between Gravelly Ford and the Mendota Pool except when flood control requires additional releases from the dam. At Mendota, water pumped from the Delta is delivered and used to rewet the river. Despite the federal Central Valley Project Act's (and the California voters') express authorization of this scheme, in 2004, a federal judge ruled the U.S. Bureau of Reclamation in violation of California law for not letting enough water flow to maintain the historic salmon population.

The San Joaquin river once supported the southernmost salmon run in North America. As a result of seasonal water diversions and the operation of upstream hydropower reservoirs, by 1928, the California Department of Fish and Game had issued a bulletin reporting that there were "very few" salmon remaining in the San Joaquin River above the Merced River and the "historical" salmon fishery that once existed had been "severely depleted." Although some sources claim that the river may have once supported large runs of both fall-run and spring-run Chinook salmon — up to 300,000 returning adults annually, — these claims appear to be greatly exaggerated, given the river's hydrology, San Joaquin Valley temperatures, and the impacts of these factors on available salmon habitat. An official with the California Department of Fish and Game stated in 1930s that the spawning gravels in the river were only sufficient to support, at most, about 15,000 returning fish. During that same time (late 1930s - early 1940s), the salmon counts taken by the California Department of Fish and Game at the Mendota Dam fish ladder showed about 3,000-7,000 salmon returning each year to spawn. While some sources claim that steelhead trout may have also been present in the river in the 19th century, there is no known evidence to confirm this speculation.

Long-stalled legislation to bring life back to the dried-up San Joaquin River and restore its historic salmon run cleared a significant hurdle Wednesday May 8th, 2008 when a U.S. Senate committee gave its approval. The settlement agreement, supported by almost every member of the California congressional delegation, anticipated spending as much as $800 million to restore a 150-mile (240 km) stretch of river. Farmers would pay about $330 million, and the rest would come from California bonds and the federal government. One possible catch is that environmentalists plan to replace the extinct San Joaquin chinook with Sacramento River salmon, which are themselves in trouble. The number of spawners in the Sacramento plummeted over the past year, prompting a total ban on salmon fishing along the California and Oregon coasts.[3]

Timeline

Year Events
1858 Miller and Lux begin acquiring riparian lands along the San Joaquin and Kings Rivers
1912 Southern Edison begins building reservoirs, dams, & powerhouses on upper San Joaquin River
1951 Delta-Mendota Canal imports water to the west side of the San Joaquin Valley, including the San Joaquin River Water Authority Exchange Contractors

See also

External links