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Yellowtail Dam is a dam across the
Bighorn River The Bighorn River is a tributary of the Yellowstone, approximately long, in the states of Wyoming and Montana in the western United States. The river was named in 1805 by fur trader François Larocque for the bighorn sheep he saw along its ...
in south central
Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Colum ...
in the
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territo ...
. The mid-1960s era concrete arch dam serves to regulate the flow of the Bighorn for
irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been develo ...
purposes and to generate hydroelectric power. The dam and its reservoir,
Bighorn Lake Bighorn Lake is a reservoir behind Yellowtail Dam within the Bighorn Canyon National Recreation Area, located in northern Wyoming and extending into southern Montana. Geography The reservoir is south of Billings, Montana. It stretches the en ...
, are owned by the
U.S. Bureau of Reclamation The Bureau of Reclamation, and formerly the United States Reclamation Service, is a federal agency under the U.S. Department of the Interior, which oversees water resource management, specifically as it applies to the oversight and opera ...
. The project was the result of negotiations between the federal government and the
Crow Nation The Crow, whose autonym is Apsáalooke (), also spelled Absaroka, are Native Americans living primarily in southern Montana. Today, the Crow people have a federally recognized tribe, the Crow Tribe of Montana, with an Indian reservation locat ...
, the tribe of Native Americans that lived on the surrounding
Crow Indian Reservation The Crow Indian Reservation is the homeland of the Crow Tribe. Established 1868, the reservation is located in parts of Big Horn, Yellowstone, and Treasure counties in southern Montana in the United States. The Crow Tribe has an enrolled member ...
, and was originally envisioned as a shared facility that would provide profits for both sides. Eventually, the land was sold to Reclamation, although much of the reservoir, which extends upstream into Wyoming, lies in the reservation. The dam was authorized in 1944 and groundbreaking was in 1961; it was completed in 1967 after six years of construction. Today aside from its original purposes the dam serves for recreation both above and below the structure. Regulation of the Bighorn provided by the Yellowtail Dam has transformed the lower river into one of Montana's premier trout streams. However, there has been significant controversy surrounding the allocation of water in the reservoir between Montana and Wyoming, and the ecological damage wrought on of river both above and below the dam.


History


Planning

In the early 20th century, the population of the
Yellowstone River The Yellowstone River is a tributary of the Missouri River, approximately long, in the Western United States. Considered the principal tributary of upper Missouri, via its own tributaries it drains an area with headwaters across the mountains an ...
valley of southern Montana, of which the Bighorn River is the largest tributary, was growing rapidly and so was the acreage of irrigated land – however, the system was vulnerable to floods and droughts. In 1905, the federal government conducted the first feasibility studies for a dam on a stretch of the Bighorn within the
Crow Indian Reservation The Crow Indian Reservation is the homeland of the Crow Tribe. Established 1868, the reservation is located in parts of Big Horn, Yellowstone, and Treasure counties in southern Montana in the United States. The Crow Tribe has an enrolled member ...
, some southeast of
Billings, Montana Billings is the largest city in the U.S. state of Montana, with a population of 117,116 as of the 2020 census. Located in the south-central portion of the state, it is the seat of Yellowstone County and the principal city of the Billings Met ...
. The leaders of the
Crow Nation The Crow, whose autonym is Apsáalooke (), also spelled Absaroka, are Native Americans living primarily in southern Montana. Today, the Crow people have a federally recognized tribe, the Crow Tribe of Montana, with an Indian reservation locat ...
, which owned the land, agreed to building a dam there because electricity generated there would provide income for the tribe. Construction of the Yellowtail Dam was authorized by the Flood Control Act on December 22, 1944 as part of the Pick-Sloan Plan, a water management scheme covering the entire upper Missouri River Basin in the north-central United States. Three proposals were then made by the Reclamation Service, the predecessor of the present-day Bureau of Reclamation, during the first half of the century. The first idea called for the building of a arch gravity dam at the present-day site. The second suggested constructing a pair of smaller dams on the river about apart. Plans for the current dam were finalized in the 1950s, as a high dam would provide a greater
hydraulic head Hydraulic head or piezometric head is a specific measurement of liquid pressure above a vertical datum., 410 pages. See pp. 43–44., 650 pages. See p. 22. It is usually measured as a liquid surface elevation, expressed in units of length, ...
, allowing water to be diverted into canals at higher elevations to serve farms both within and downstream of the Crow lands. The dam is named after
Robert Yellowtail Robert Summers Yellowtail (August 4, 1889 – June 20, 1988) was a leader of the Crow Nation. Described as a "20th Century Warrior", Yellowtail was the first Native American to hold the post of Agency Superintendent at a reservation. Early ...
, chairman of the tribe during the 1940s. Yellowtail was one of the main opponents of the dam and also protested when the tribe decided to sell the dam site to the federal government. For a while, the Crow Nation considered leasing the land to the government for fifty years at a rate of $1,000,000 per year. The arguments deeply divided the tribe, causing them to separate into two factions, the Mountain Crows, which backed Yellowtail and opposed the dam, and the River Crows, which supported the dam. Eventually, the land was sold for $2.5 million, and controversy continued for years afterward.


Construction

Boise, Idaho based Morrison-Knudsen, at the time the largest heavy contractor in the world, landed the contract to build the dam. Morrison-Knudsen had previously built the Hoover and Grand Coulee Dams. Official groundbreaking for the Yellowtail Dam was in 1961 and the construction of a diversion tunnel was begun soon afterwards. The concrete-lined conduit ultimately extended over and had a diameter of . A cofferdam was then raised to divert the Bighorn out of the dam site into the tunnel. The first concrete pour was on March 16, 1963, and the diversion tunnel was closed in November 1965, allowing the river to begin filling Bighorn Lake. In the same year, the Yellowtail Afterbay Dam, serving to regulate releases from the main dam was completed downstream of Yellowtail Dam. The Yellowtail Dam was topped out in December 1967 after six years of work. Surprisingly, for such a huge structure, only one death occurred during the entire construction process.


Characteristics


Dam and reservoir

The Yellowtail Dam is a concrete thin-arch dam high and long, containing of material. The crest of the dam lies above sea level.
As the crow flies __NOTOC__ The expression ''as the crow flies'' is an idiom for the most direct path between two points, rather similar to "in a beeline". This meaning is attested from the early 19th century, and appeared in Charles Dickens's 1838 novel ''Olive ...
, the dam is southeast of Billings and north of the Montana-Wyoming border. The dam and reservoir lie in Bighorn Canyon in the northwestern portion of the Bighorn Range where the Bighorn River cuts through it, above the Bighorn's junction with the Yellowstone at Custer, Montana.
Bighorn Lake Bighorn Lake is a reservoir behind Yellowtail Dam within the Bighorn Canyon National Recreation Area, located in northern Wyoming and extending into southern Montana. Geography The reservoir is south of Billings, Montana. It stretches the en ...
is the reservoir formed behind the dam, and has a capacity of of water. At normal storage the reservoir covers , extending over upstream. The lake is long and narrow, except for the uppermost section near Kane, Wyoming where it broadens to about . Aside from the Bighorn River the reservoir is also fed by the
Shoshone River The Shoshone River is a long river in northern Wyoming in the United States. Its headwaters are in the Absaroka Range in Shoshone National Forest. It ends when it runs into the Big Horn River near Lovell, Wyoming. Cities it runs near or ...
, Porcupine Creek, Dry Head Creek, Big Bull Elk Creek, Black Canyon Creek, and smaller tributaries.


Power generation

The dam's hydroelectric plant is located at the base and has a capacity of 250 MW. The plant has four
Francis turbine The Francis turbine is a type of water turbine. It is an inward-flow reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today, and can achieve over 95% efficiency. The process ...
s rated at 87,500
horsepower Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are th ...
, each capable of driving a 62,500 KW generator. The
hydraulic head Hydraulic head or piezometric head is a specific measurement of liquid pressure above a vertical datum., 410 pages. See pp. 43–44., 650 pages. See p. 22. It is usually measured as a liquid surface elevation, expressed in units of length, ...
is roughly at normal reservoir elevation. Operations of the facility began in 1966, one year before the completion of the dam. The power station is used based on
peaking power Peaking power plants, also known as peaker plants, and occasionally just "peakers", are power plants that generally run only when there is a high demand, known as peak demand, for electricity. Because they supply power only occasionally, the power ...
demand and thus releases can vary drastically over the course of a day. The Yellowtail Afterbay dam, built for the purpose of regulating the fluctuating discharge from the power station, lies below the main dam and can store of water. This dam generally releases a constant flow of into the Bighorn.


Spillway

To pass flood waters the Yellowtail Dam is equipped with a tunnel spillway on the left side, capable of handling . The spillway is controlled by a pair of
radial gate The Tainter gate is a type of radial arm floodgate used in dams and canal locks to control water flow. It is named for Wisconsin structural engineer Jeremiah Burnham Tainter. A side view of a Tainter gate resembles a slice of pie with the ...
s measuring high and long. The dam also has a set of
outlet works A gatehouse, gate house, outlet works or valve house for a dam is a structure housing sluice gates, valves, or pumps (in which case it is more accurately called a pumping station). Many gatehouses are strictly utilitarian, but especially in the ni ...
that can discharge up to . In 1967, heavy snowmelt in the Bighorn River basin caused the reservoir to rise to record levels. Reclamation opened the spillway of the dam for twenty consecutive days in June and July of that year. However, the design of the spillway tunnel was flawed, causing severe cavitation of the concrete, leading to the formation of a hole the size of an eighteen-wheeler in the concrete lining. The resulting repairs and retrofits to the spillway were the vital predecessor to the repair work to dams such as Hoover,
Glen Canyon Glen Canyon is a natural canyon carved by a length of the Colorado River, mostly in southeastern and south-central Utah, in the United States. Glen Canyon starts where Narrow Canyon ends, at the confluence of the Colorado River and the Dirty D ...
and Flaming Gorge that would follow severe floods in 1983 in the
Colorado River The Colorado River ( es, Río Colorado) is one of the principal rivers (along with the Rio Grande) in the Southwestern United States and northern Mexico. The river drains an expansive, arid watershed that encompasses parts of seven U.S. sta ...
basin.


Recreation

Although unplanned for, by regulating the flow of the Bighorn River and releasing cooler water from the bottom of Bighorn Lake, the Yellowtail Dam has created one of the finest wild
trout Trout are species of freshwater fish belonging to the genera ''Oncorhynchus'', ''Salmo'' and ''Salvelinus'', all of the subfamily Salmoninae of the family Salmonidae. The word ''trout'' is also used as part of the name of some non-salmonid ...
fisheries in the United States in the slightly more than of river downstream. However, the dam has significantly changed the native riverine habitat downstream as well – cutting off the supply of sediments, which once created islands and sandbars in the Bighorn's winding lower course. Nevertheless, the combination of cold, fast-flowing water and abundant nutrients creates an ideal trout habitat; the average length of a trout caught in the lower Bighorn is , while the record was a
rainbow trout The rainbow trout (''Oncorhynchus mykiss'') is a species of trout native to cold-water tributaries of the Pacific Ocean in Asia and North America. The steelhead (sometimes called "steelhead trout") is an anadromous (sea-run) form of the coasta ...
long. In recent years there has been controversy between Montana and Wyoming over whether more water should be kept in Bighorn Lake for boating and water-skiing uses (almost two-thirds of the surface area of Bighorn Lake is in Wyoming), or released from the dam to maintain the trout fishery downstream. Because of a long and ongoing drought in the western United States, Reclamation has reduced the amount of water below the Yellowtail Dam from to . The lower flows have led to unhealthy trout populations in turn causing the fishing industry on the lower Bighorn to decline by over 40 percent. However, low water levels in the lake have caused recreational usage in Wyoming to drop more than 60%. In an attempt to reduce tensions between the two states Reclamation has agreed to keep the lake at a higher level while maintaining at least of flow below the dam.


See also

*
Bighorn Basin The Bighorn Basin is a plateau region and intermontane basin, approximately 100 miles (160 km) wide, in north-central Wyoming in the United States. It is bounded by the Absaroka Range on the west, the Pryor Mountains on the north, the Big ...
* *
List of reservoirs and dams in the United States The following is a partial list of dams and reservoirs in the United States. There are an estimated 84,000 dams in the United States, impounding of river or about 17% of rivers in the nation. By state Alabama Alaska Arizona Arkan ...


References


Works cited

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External links

* Series 29: Yellowtail Dam #1. {{authority control Dams in Montana Hydroelectric power plants in Montana Buildings and structures in Big Horn County, Montana United States Bureau of Reclamation dams Bighorn Canyon National Recreation Area Reservoirs and dams in National Park Service units Dams completed in 1967 1967 establishments in Montana