The Kings River () is a river draining the Sierra Nevada mountain range in central California in the United States. Its headwaters originate along the Sierra Crest in and around Kings Canyon National Park and form Kings Canyon, one of the deepest river gorges in North America. The river is impounded in Pine Flat Lake before flowing into the San Joaquin Valley (the southern half of the Central Valley) southeast of Fresno. With its upper and middle course in Fresno County, the Kings River diverges into multiple branches in Kings County, with some water flowing south to the old Tulare Lake bed and the rest flowing north to the San Joaquin River. However, most of the water is consumed for irrigation well upstream of either point.
Inhabited for thousands of years by the Yokuts and other native groups, the Kings River basin once fed a vast network of seasonal wetlands around Tulare Lake that supported millions of waterfowl, fish, and game animals, in turn providing sustenance for indigenous peoples. Tulare Lake was once the largest freshwater lake in the western U.S., at the middle of an endorheic basin also fed by the Kaweah, Tule and Kern Rivers. The river was named by Gabriel Moraga, the commander of a Spanish military expedition in 1806, but it was not until California became a U.S. state in 1850 that many Europeans arrived and settled along the Kings River, driving out the area's original inhabitants. Logging and livestock grazing inflicted significant environmental damage on the upper parts of the river system, before the federal government moved to establish national parks and preserves there.
The Kings has a long history of water development, going back to the mid-19th century when farmers made their first attempts to irrigate with Kings River water. In the early 1900s Tulare Lake and its surrounding wetlands were diked, drained and reclaimed for agriculture; the construction of Pine Flat Dam in the 1950s tamed the river's seasonal floods. The battle for control over Kings River water produced extended conflicts, including a set of dams proposed in what would become Kings Canyon National Park. Today, the river irrigates about 1.1 million acres (4,500 km2) of some of the most productive farmland in the country, and is also used extensively for hydropower generation, and water-based and backcountry recreation.
Course All three forks of the Kings River originate as snowmelt in the high Sierra Nevada mountains. The Middle and South Forks begin in Kings Canyon National Park, and join in the Monarch Wilderness (Sierra and Sequoia National Forests) to form the Kings River. The North Fork, which begins in the John Muir Wilderness of the Sierra National Forest, joins the Kings River further downstream near Pine Flat Lake, the only major reservoir on the river. Much of the upper Kings River consists of remote backcountry and wilderness areas, accessible only by non-motorized trails. The entire upper course of the Kings River is in Fresno County; in the Central Valley, the Kings River also flows through parts of Tulare County and Kings County.
Headwaters The South Fork is the longest tributary of the Kings River, originating on the Sierra Crest at the far eastern edge of Kings Canyon National Park. It flows south, then flows west through the Cedar Grove section of Kings Canyon, a glacial valley with high granite cliffs and a meadow floor which has been compared in appearance to Yosemite Valley.
The Middle Fork flows for through some of the park's most difficult-to-access backcountry, including Simpson Meadow and Tehipite Valley. The South and Middle Forks converge in the Monarch Wilderness at an elevation of just outside the national park to form the Kings River in the deepest part of Kings Canyon. With Spanish Peak towering above the north side of the river, and summits as high as on the south side, Kings Canyon is both deeper and narrower than the Grand Canyon.
Below the confluence of the Middle and South Forks, the Kings River flows swiftly westward for about , carving a canyon more than deep in places. Major tributaries of the Kings River in this section include Tenmile and Mill Flat Creeks, both from the south; a dam on Tenmile Creek creates Hume Lake. Another notable feature along this area of the Kings Canyon is Garlic Falls, a tiered waterfall on a tributary of the Kings more than in height. The canyon is roadless as far as the Upper Kings Campground near Verplank Creek; below the campground the river is followed by Trimmer Springs Road.
The Kings River passes Rodgers Crossing and receives the North Fork from the right near Balch Camp. The North Fork is about long and flows mainly through the Sierra National Forest. It is dammed at Wishon Reservoir, which serves as the lower reservoir for the Helms Pumped Storage Plant, one of the biggest pumped-storage hydroelectric plants in California. The North Fork passes through several other hydro plants before it joins with the Kings River. The main Kings then flows into Pine Flat Lake, the large reservoir created by Pine Flat Dam, which can store up to of water. Constructed in 1954, Pine Flat Dam provides flood control, irrigation and hydroelectricity for the southern San Joaquin Valley.
Lower river The Kings River emerges from the foothills of the Sierra Nevada near Piedra, about downstream of Pine Flat Dam. From there it flows across the gently sloping alluvial plain of the San Joaquin Valley, which today is one of the most productive agricultural regions of the United States. Here the Kings River encounters a large number of diversions that serve both irrigation and flood control purposes. Two key irrigation structures along the lower river are the Fresno Weir and People's Weir; both divert a substantial part of the river's flow into canals. The Kings River flows south-southwest past Sanger and Reedley, crossing briefly into northwest Tulare County before entering Kings County. At Kingsburg Cole Slough splits off to the northwest, rejoining the main stem about downstream at Laton.
About north of Lemoore the Kings River splits into a pair of distributaries, the North Fork and the South Fork (not to be confused with the North and South Forks upstream in the Sierra Nevada). The Army Weir controls the amount of water flowing into the South Fork and North Fork's flow is controlled by Island Weir, which is adjacent to Army Weir. Fresno Slough diverges from the North Fork and flows northwest, seasonally carrying floodwaters from the Kings River to the San Joaquin River at Mendota. This is the only branch of the Kings River to reach the San Joaquin, and consequently the Pacific Ocean. The remainder of the North Fork turns south below Fresno Slough, rejoining the South Fork west of Lemoore. There is also a smaller distributary called Clark's Fork which splits from the South Fork and enters the North Fork just above where all the forks re-join.
From there the Kings River flows due south through Kings County, past Stratford, and approaches the old Tulare Lake bed. The river terminates about northeast of Kettleman City at a junction with a canal carrying water from the Tule River. Today, the old lake bed is used for agriculture and diked to prevent flooding; floodwaters are pumped into about of evaporation basins. In most years, the dams on the Kings and other rivers flowing into Tulare Lake, and the extensive canal diversion system surrounding the lake, are sufficient to prevent flooding. However, the lake occasionally reforms in very wet years.
Watershed and natural characteristics
The Kings River is the largest river draining the southern Sierra Nevada. Its average annual flow of makes it larger than the Kern, Kaweah and Tule Rivers combined. Before the construction of Pine Flat Dam in 1954, the Kings River reached monthly averages as high as in May and June where it flows into the San Joaquin Valley, and averaged as low as in the driest months of September and October. After the dam was built, late spring-early summer high flows have been reduced, and late summer-autumn flows have greatly increased.
In the winter season of mid-November through April, rainstorms at lower elevations commonly flood the Kings River, although with less volume than the summer melt. Annual precipitation can be as high as in the Sierra; however, in the San Joaquin Valley the climate is semi-arid to arid with annual precipitation of , decreasing as one moves further west.
The majority of the runoff, about 71 percent, originates as snowmelt between April and July in the drainage basin above Pine Flat Dam. Three-quarters of this rugged watershed is a mile (1,600 m) or more above sea level; the watershed tops out at North Palisade, the highest point in Kings Canyon National Park. The canyons of the Kings River are relatively young in geological terms; mostly carved during the Pliocene and Pleistocene (5 million–12,000 years ago) during periods of rapid uplift in the Sierra Nevada.
During and before the Pleistocene, the upper portion of the watershed was heavily glaciated during successive ice ages, with valley glaciers flowing as much as down the river's three forks, carving the V-shaped river canyons into the U-shaped gorges of Kings Canyon, Tehipite Valley and others. The Sierra is composed mainly of granitic igneous rock; however, in the foothill area the Kings River flows through roof pendant formations of older sedimentary and metamorphic rock which were accreted to the Sierra Nevada crustal block as it rose above the surrounding landscape.
The lower Kings River forms a large and gently sloping inland delta, or alluvial fan, extending laterally across the Central Valley – the resulting material from millions of years of erosion that carved Kings Canyon. The alluvial fan raised the elevation of the valley floor and blocked water flowing northward into the San Joaquin River, essentially creating a large bowl in the southern part of the valley, forming the Tulare Lake basin. Soils on the alluvial slope are generally sandy, permeable and fertile, creating ideal conditions for farming; in lower elevations and old lake beds the soil is more alkaline and less fertile.
Before people began building levees and dikes in the 19th century to contain flooding, the Kings River experienced frequent channel avulsion during high flow events, sometimes flowing north into the San Joaquin River via various sloughs, at other times south into Tulare Lake, and often into both. Historically, the river had a wide floodplain characterized by a system of vernal pools, oxbow lakes, and seasonal channels and marshes that supported a dense riparian habitat. The overflow area began near present-day Kingsburg and continued from there south to Tulare Lake.
In extremely wet years, Tulare Lake could fill to such an extent that it backed up the lower Kings River and overflowed through Fresno Slough into the San Joaquin River. All this intermittent flooding over thousands of years built up the valley's huge groundwater reserves, which today are a vital water source for agriculture. The Kings Subbasin aquifer, as defined by the California Department of Water Resources, contained in 1961 a total of , a level that has since been gradually declining due to intensive pumping for irrigation.