Flaming Gorge Dam
|Flaming Gorge Dam|
The Flaming Gorge Dam
|Location||Flaming Gorge National Recreation Area, Daggett County, Utah|
|Construction cost||$115 million|
|Owner(s)||U.S. Bureau of Reclamation|
|Dam and spillways|
|Type of dam||Concrete thin-arch|
|Length||1,180 feet (360 m)|
|Height||502 feet (153 m)|
|Width (crest)||27 feet (8.2 m)|
|Width (base)||131 feet (40 m)|
|Dam volume||986,000 cubic yards (754,000 m3)|
|Spillway type||Tunnel, twin gates|
|Spillway capacity||28,800 cubic feet per second (820 m3/s)|
|Creates||Flaming Gorge Reservoir|
|Total capacity||3,788,700 acre feet (4.6733×109 m3)|
|Catchment area||15,000 square miles (39,000 km2)|
|Surface area||42,020 acres (170.0 km2)|
|Turbines||3x Francis turbines|
|Installed capacity||153 MW|
|Annual generation||344,369,058 KWh|
The Flaming Gorge Dam is a concrete thin-arch dam in the Flaming Gorge National Recreation Area of the Green River, a major tributary of the Colorado River, in the U.S. state of Utah. Flaming Gorge Dam forms the Flaming Gorge Reservoir, which extends 91 miles (146 km) into southern Wyoming, submerging four distinct gorges of the Green River. The dam is a major component of the Colorado River Storage Project, which stores and distributes upper Colorado River Basin water.
Situated in Flaming Gorge, a canyon of the Green River named by John Wesley Powell, the dam was built and operated by the U.S. Bureau of Reclamation. Construction began in 1958 and was completed in 1964. The dam is 502 feet (153 m) high and 1,180 feet (360 m) long, and its reservoir has a capacity of more than 3.7 million acre feet (4.6 km3), or about twice the annual flow of the upper Green. The dam is a major source of hydroelectricity and is the main flood-control facility for the Green River system.
The Flaming Gorge Reservoir is a popular recreation spot and one of Utah's greatest fisheries. The Green River below the dam is also considered a "Blue Ribbon Trout Fishery" and a good whitewater stream.
The dam has fragmented the upper Green River, blocking fish migration and significantly impacting many native species. Water released from the dam is generally cold and clear, as compared to the river's natural warm and silty flow, further changing the local riverine ecology.
The Green River flows 730 miles (1,170 km) from its headwaters in the Wind River Mountains of Wyoming, primarily south to its confluence with the Colorado River in Canyonlands National Park. Near the town of Green River, Wyoming, the river leaves its broad valley and flows through four major canyons - including Red Canyon and Flaming Gorge - then looping east into Colorado, slicing through the Uinta Mountains. Just downstream of the confluence with Cart Creek, (where Cart Creek Bridge now stands), the Green turns south and enters a section where the canyons become extremely narrow, only 1,000 to 1,500 feet (300 to 460 m) wide. The Flaming Gorge Dam was built in this canyon in 1964.
The Flaming Gorge area was prehistorically inhabited by people of the Fremont culture, which hunted game near Flaming Gorge, during prehistoric periods. The Ute tribes came later and spread throughout mountainous regions in what are now the present-day states of Colorado and Utah. In the early 19th century, fur trappers began searching the area for beaver. This led to the first exploration of the Green River, by William H. Ashley, one of the organizers of the Rocky Mountain Fur Company. Far later, in 1869, famed explorer John Wesley Powell and nine men started an expedition of the Green River and the Colorado River. Powell gave Flaming Gorge its present name after seeing the "sun reflecting off the red rocks", although Red Canyon, was to them, more impressive than Flaming Gorge, with its far more dangerous rapids. With new knowledge of the area, ranchers and pioneers moved to the area beginning in the 1870s. Many outlaws and fugitives, including Butch Cassidy and the Wild Bunch, would hide in isolated canyons along the Green River.
The cancellation of Echo Park Dam, a proposal in the scenic downstream Green River canyon of Echo Park, was won by environmentalists primarily from the Sierra Club, at that time led by David Brower. Having never seen Flaming Gorge and Glen Canyon until construction had begun on both dams, Brower had suggested that a "sacrifice" should be made in order to preserve Echo Park. The famous quote:
prompted Congress to reject this proposal. However, when both dams had already begun construction, it was said that Brower vowed to
never again … compromise over such a dam.
Although Flaming Gorge is nowhere as well known as Glen Canyon, he had still quoted it as "part" of the sacrifice. While Glen Canyon was the primary "replacement", Flaming Gorge provided additional storage.
Construction of the Flaming Gorge Dam began in 1958 under the direction of the Bureau of Reclamation, and ended in 1964 with the completion of its three generators, each rated at 36,000 kilowatts. The town of Dutch John, with a population of three thousand at the peak of construction, was a company town built to house construction workers. The reservoir first filled to its highest capacity in August 1974. The construction of the dam resulted in permanent changes to the ecosystem of the Green River. 91 miles (146 km) of the river was flooded to become Flaming Gorge Reservoir. Prior to the construction of the dam, the Green was a highly seasonal, silty and warm river, with greatly fluctuating flows throughout the year. After the dam was built, the river temperature dropped and silt was trapped in the reservoir. Sandbars downstream of the dam ceased to replenish and the habitat of native fish disappeared, in similar fashion to the Grand Canyon when Glen Canyon Dam was built. Despite the lower Green being a "Blue Ribbon Trout Fishery", many native fish have been lost.
On August 11, 1977, one of the turbines, Unit 2, jammed after one of the sealing rings on the penstock failed. This event led to the seal rings on all three penstocks being replaced. These seal rings also failed, and were replaced again. However, no major structural damage to the dam occurred. The generators were uprated to 50,650 kilowatts each from August 1990 to April 1992.
Dimensions and operations
The Flaming Gorge Dam is 502 feet (153 m) high above the Green River. It measures 1,180 feet (360 m) long along its crest and its maximum base thickness is 131 feet (40 m), while its crest thickness is 27 feet (8.2 m). The dam contains about 987,000 cubic yards (755,000 m3) of concrete. The reservoir of the dam is approximately 6,040 feet (1,840 m) in elevation at full pool.
The dam's hydroelectric power plant is located at its base. It consists of three 50,650 kilowatt generators, powered by three Francis design turbines of 50,000 horsepower (37,000 kW). The total nameplate generating capacity of the Flaming Gorge Dam is 151,950 kilowatts. Three 10 feet (3.0 m) diameter penstocks feed water to the power plant. The Bureau of Reclamation operates the power plant, and the Western Area Power Administration markets the power generated by the dam.
Excess water is spilled through a 675-foot (206 m) long tunnel spillway that runs through the left abutment of the dam. Controlled by two 16.75-foot (5.11 m) by 34-foot (10 m) gates, the tunnel has a capacity of 28,800 cubic feet (820 m3) per second. At its upstream end it is 26.5 feet (8.1 m) in diameter, and at the discharge point is 18 feet (5.5 m) in diameter. The dam also has an outlet works, which consists of two 72-inch (1.8 m) diameter steel pipes through the dam. The discharge capacity of the outlet works is 4,000 cubic feet (110 m3) per second.
The cold and sediment-lacking water released from the Flaming Gorge Dam, which averages from 800 cubic feet (23 m3) to 4,700 cubic feet (130 m3) per second, has caused loss of sandbars, sediment, and as a result crucial habitat of four species of native fish, in the lower Green River. Introduced brown trout, rainbow trout, and lake trout have caused increased damage to these habitats. On August 28, 2008, the Bureau of Reclamation prepared an EIS (Environmental Impact Statement) on the operation of the dam to meet the river flow required by the Recovery Implementation Program for Endangered Fish Species and Section 7 of the Endangered Species Act. The four native fishes affected by Flaming Gorge and Glen Canyon dams are: the razorback sucker, Colorado pikeminnow, humpback chub, and bonytail chub.
In 2006, the dam began a release pattern more similar to historical discharges along the Green River, intended to assist the dropping native fish populations.
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Media related to Flaming Gorge Dam at Wikimedia Commons