Плотина Пайн-Флэт: История строительства и значение для Калифорнии

Pine Flat Dam is a concrete gravity dam on the Kings River in the Central Valley of Fresno County, California United States. Situated about 28 mile (45 km) east of Fresno, the dam is 440 feet (134 m) high and impounds Pine Flat Lake, in the foothills of the Sierra Nevada just outside the boundary of Kings Canyon National Park. The dam's primary purpose is flood control, with irrigation, hydroelectric power generation and recreation secondary in importance. The dam was built by the U. S. Army Corps of Engineers (USACE) after a six year controversy between supporters of irrigation development and proponents of flood control. Construction began in 1947 and was completed in 1954. Since then, the dam has prevented millions of dollars in flood damages and fostered extensive development of agriculture on the fertile floodplain of the Kings River; after 1984 it has also generated hydroelectricity. The increased irrigation allowed by the dam has also led to the destruction of some of North America's most extensive wetland habitats.

The first serious proposal to dam the Kings River was made in the 1890s by engineer J. B. Lippincott, who surveyed and envisioned the development of a reservoir on the river. By 1914 the proposed dam gained strong support from area farmers and water districts, who formed the Kings River Water Association (KRWA) in 1927 to allocate river water for the irrigation of of the San Joaquin Valley on the alluvial plain of the Kings River. In 1937, the KRWA appealed to the federal government to provide financial aid and support the construction of a large dam at Pine Flat.

By 1940 the water users of the Kings River were leaning towards letting the USACE build the dam, in light of the continual water rights problems associated with the USBR's plans, in addition to full federal funding offered by the USACE. The Flood Control Act of 1944 cemented this decision, authorizing the construction of four dams in the Tulare Lake basin of the San Joaquin Valley – Pine Flat, Terminus, Success and Isabella – as a USACE undertaking. The president signed a bill appropriating preliminary funds for Pine Flat Dam on April 2, 1945, but only "reluctantly" and "[with the emphasis] that he'd try to avoid dispensing any more money to the army for the dam". Roosevelt planned to take the Pine Flat issue to Congress, but never got the chance – he died of a brain hemorrhage just ten days later at his home in Georgia. Roosevelt's successor, Harry S. Truman, was also adamant that Pine Flat Dam be built for irrigation. Truman impounded the initial funds for the dam's construction and promised not to release it until the USACE and USBR could reach an agreement on the proportions of funding that would go to irrigation and flood control. To further complicate the situation, Truman insisted that the USBR negotiate the contracts for irrigation water from Pine Flat Dam with KRWA farmers. In 1951, a cofferdam was constructed to divert the Kings River along the north side of the canyon to allow the construction of the dam's foundations. In July, the river was blocked from this temporary channel and flowed through the dam's bottom sluice gates for the first time, permitting the northern section of the dam to be built in the former diversion channel. By 1953, the dam was high enough to begin impounding the river and flows through the sluice gates were cut, and the lake began to fill. In January 1969, the highest releases ever from Pine Flat Dam, , occurred in the wake of a flood that reached a less impressive peak of but had a much greater volume than the 1955 rain flood. The lake, which once comprised nearly of seasonal open water and wetlands, was reduced to less than by 1960. During the 1969 rains local residents clamored for floodwaters from Pine Flat Lake to be diverted to Tulare lakebed. Representation on the irrigation district board, however, was determined by the value of landowners’ land and J. G. Boswell Company owned the majority of land in the district. J. G. Boswell Co. voted to block the floodwater diversion so that its crops on the Buena Vista lakebed would not be destroyed. Residents whose homes were destroyed by the flood sued. Limiting suffrage to landowners violated the one man, one vote guarantee in the U. S. Constitution, they alleged, because the irrigation district can levy taxes, exercise eminent domain, and decide whose land gets flooded. In 1973 a divided United States Supreme Court disagreed, finding that a private company can exercise control of the irrigation district because flood control is not an important government function. In the early 1970s, the Kings River Conservation District (KRCD) proposed a system of new dams and power plants to further develop the water resources of the Kings River watershed. These included a new power station at Pine Flat Dam, a 600 feet (183 m) dam at Rodgers Crossing upstream of Pine Flat Lake and a reservoir at Piedra to regulate Pine Flat Dam releases. The only part of the project to be completed was the Jeff L. Taylor Pine Flat Power Plant at the base of Pine Flat Dam, which went into operation in 1984.

Pine Flat Dam is a solid concrete gravity structure that stands 440 feet (134 m) high from foundations and 424 feet (129 m) high above the Kings River. Due to the limited capacity of the reservoir, dam operators are often forced to release flows that exceed this limit in high runoff years, including in 1969, 1978, and 1986. In the 1969 floods, of water – greater than the entire capacity of Pine Flat Lake – poured over the dam's spillway. An average of of water is spilled each year, reducing valuable irrigation water supplies and causing flooding, because Pine Flat Dam is unable to contain it. The dam is also operated to maintain base flows in the Kings River during low water summers for wildlife conservation purposes. On September 11, 1964, the California Department of Fish and Game and the KRWA signed an agreement that established a minimum release of , which can be reduced to if inflows from downstream tributaries exceed that amount.