Yellowtail Dam
Encyclopedia
Yellowtail Dam is a dam across the Bighorn River
in southwestern Montana
in the United States
. The mid-1960s era concrete arch dam
serves to regulate the flow of the Bighorn for irrigation
purposes and to generate hydroelectric power
. The dam and its reservoir, Bighorn Lake
, are owned by the U.S. Bureau of Reclamation.
The project was the result of negotiations between the federal government and the Crow Nation
, the tribe of Native Americans that lived on the surrounding Crow Indian Reservation
, 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 72 miles (115.9 km) 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 184 miles (296.1 km) of river both above and below the dam.
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
, some 45 miles (72.4 km) southeast of Billings, Montana
. The leaders of the Crow Nation
, 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 480 feet (146.3 m) arch gravity dam at the present-day site. The second suggested constructing a pair of smaller dams on the river about 70 miles (112.7 km) apart. Plans for the current dam were finalized in the 1950s, as a high dam would provide a greater hydraulic head
, 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, chairman of the tribe during the 1940s. Ironically, Yellowtail was one of the largest 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.
, the dam is 45 miles (72.4 km) southeast of Billings and 23 miles (37 km) 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, 112 miles (180.2 km) above the Bighorn's junction with the Yellowstone at Custer, Montana
.
Bighorn Lake
is the reservoir formed behind the dam, and has a capacity of 1381189 acre.ft of water. At normal storage the reservoir covers 17300 acres (70 km²), extending over 70 miles (112.7 km) upstream. The lake is long and narrow, except for the uppermost section near Kane, Wyoming
where it broadens to about 2 miles (3.2 km). Aside from the Bighorn River the reservoir is also fed by the Shoshone River
, Porcupine Creek, Dry Head Creek, Big Bull Elk Creek, Black Canyon Creek, and smaller tributaries.
s rated at 87,500 horsepower
, each capable of driving a 62,500 KW generator. The hydraulic head
is roughly 495 feet (150.9 m) 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 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 2.2 miles (3.5 km) below the main dam and stores 3140 acre.ft of water. The dam generally releases a constant flow of 2500 cuft/s into the Bighorn.
that can discharge up to 2500 cuft/s.
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 a 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
and Flaming Gorge
that would follow severe floods in 1983 in the Colorado River
basin.
fisheries in the United States in the slightly more than 110 miles (177 km) 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 14 inches (35.6 cm), while the record was a 16 pounds (7.3 kg) rainbow trout
29 inches (73.7 cm) 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 2500 cuft/s to 2000 cuft/s. 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 1500 cuft/s of flow below the dam.
Bighorn River
The Bighorn River is a tributary of the Yellowstone, approximately long, in the western United States in the states of Wyoming and Montana. The river was named in 1805 by fur trader François Larocque for the Bighorn Sheep he saw along its banks as he explored the Yellowstone River.The upper...
in southwestern Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. The mid-1960s era concrete arch dam
Arch dam
An arch dam is a type of dam that is curved and commonly built with concrete. The arch dam is a structure that is designed to curve upstream so that the force of the water against it, known as hydrostatic pressure, presses against the arch, compressing and strengthening the structure as it pushes...
serves to regulate the flow of the Bighorn for irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...
purposes and to generate hydroelectric power
Hydroelectricity
Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy...
. The dam and its reservoir, Bighorn Lake
Bighorn Lake
Bighorn Lake is a reservoir in the United States located in Southern Montana and Northern Wyoming in the Bighorn Canyon National Recreation Area. The lake is 40 mi south of Billings, Montana. Bighorn Lake was created by the construction of Yellowtail Dam near Fort Smith, Montana in 1965...
, are owned by the U.S. Bureau of Reclamation.
The project was the result of negotiations between the federal government and the Crow Nation
Crow Nation
The Crow, also called the Absaroka or Apsáalooke, are a Siouan people of Native Americans who historically lived in the Yellowstone River valley, which extends from present-day Wyoming, through Montana and into North Dakota. They now live on a reservation south of Billings, Montana and in several...
, the tribe of Native Americans that lived on the surrounding Crow Indian Reservation
Crow Indian Reservation
The Crow Indian Reservation is the homeland of the Crow Tribe of Indians of the State of Montana in the United States. The reservation is located in parts of Big Horn, Yellowstone, and Treasure counties in southern Montana...
, 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 72 miles (115.9 km) upstream into Wyoming
Wyoming
Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...
, 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 184 miles (296.1 km) of river both above and below the dam.
Planning
In the early 20th century, the population of the Yellowstone RiverYellowstone River
The Yellowstone River is a tributary of the Missouri River, approximately long, in the western United States. Considered the principal tributary of the upper Missouri, the river and its tributaries drain a wide area stretching from the Rocky Mountains in the vicinity of the Yellowstone National...
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
Crow Indian Reservation
The Crow Indian Reservation is the homeland of the Crow Tribe of Indians of the State of Montana in the United States. The reservation is located in parts of Big Horn, Yellowstone, and Treasure counties in southern Montana...
, some 45 miles (72.4 km) southeast of Billings, Montana
Billings, Montana
Billings is the largest city in the U.S. state of Montana, and is the principal city of the Billings Metropolitan Area, the largest metropolitan area in over...
. The leaders of the Crow Nation
Crow Nation
The Crow, also called the Absaroka or Apsáalooke, are a Siouan people of Native Americans who historically lived in the Yellowstone River valley, which extends from present-day Wyoming, through Montana and into North Dakota. They now live on a reservation south of Billings, Montana and in several...
, 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
Missouri River
The Missouri River flows through the central United States, and is a tributary of the Mississippi River. It is the longest river in North America and drains the third largest area, though only the thirteenth largest by discharge. The Missouri's watershed encompasses most of the American Great...
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 480 feet (146.3 m) arch gravity dam at the present-day site. The second suggested constructing a pair of smaller dams on the river about 70 miles (112.7 km) apart. Plans for the current dam were finalized in the 1950s, as a high dam would provide a greater hydraulic head
Hydraulic head
Hydraulic head or piezometric head is a specific measurement of water pressure above a geodetic datum. It is usually measured as a water surface elevation, expressed in units of length, at the entrance of a piezometer...
, 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, chairman of the tribe during the 1940s. Ironically, Yellowtail was one of the largest 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
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 2000 feet (609.6 m) and had a diameter of 32 feet (9.8 m). 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 2.2 miles (3.5 km) 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.Dam and reservoir
The Yellowtail Dam is a concrete thin-arch dam 525 feet (160 m) high and 1480 feet (451.1 m) long, containing 1545664 cubic yards (1,181,744.9 m³) of material. The crest of the dam lies 3660 feet (1,115.6 m) above sea level. As the crow fliesAs the crow flies
"As the crow flies" or beelining is an idiom for the shortest route between two points; the geodesic distance.An example is the great-circle distance between Key West and Pensacola, at either end of the U.S...
, the dam is 45 miles (72.4 km) southeast of Billings and 23 miles (37 km) 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, 112 miles (180.2 km) above the Bighorn's junction with the Yellowstone at Custer, Montana
Custer, Montana
Custer is a census-designated place in Yellowstone County, Montana, United States. The population was 145 at the 2000 census.This community bears the name of U.S...
.
Bighorn Lake
Bighorn Lake
Bighorn Lake is a reservoir in the United States located in Southern Montana and Northern Wyoming in the Bighorn Canyon National Recreation Area. The lake is 40 mi south of Billings, Montana. Bighorn Lake was created by the construction of Yellowtail Dam near Fort Smith, Montana in 1965...
is the reservoir formed behind the dam, and has a capacity of 1381189 acre.ft of water. At normal storage the reservoir covers 17300 acres (70 km²), extending over 70 miles (112.7 km) upstream. The lake is long and narrow, except for the uppermost section near Kane, Wyoming
Kane, Wyoming
Kane is a town that existed two miles south of the confluence of the Shoshone River and the Bighorn River in Big Horn County, Wyoming. Prior to the completion of the Yellowtail Dam in Montana, the residents of Kane sold their homes and land to the federal government. When the dam was completed the...
where it broadens to about 2 miles (3.2 km). Aside from the Bighorn River the reservoir is also fed by the Shoshone River
Shoshone River
The Shoshone River is 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 through are Cody, Powell, Byron, and Lovell. Near Cody, it...
, 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 turbineFrancis turbine
The Francis turbine is a type of water turbine that was developed by James B. Francis in Lowell, Massachusetts. It is an inward-flow reaction turbine that combines radial and axial flow concepts....
s rated at 87,500 horsepower
Horsepower
Horsepower is the name of several units of measurement of power. The most common definitions equal between 735.5 and 750 watts.Horsepower was originally defined to compare the output of steam engines with the power of draft horses in continuous operation. The unit was widely adopted to measure the...
, each capable of driving a 62,500 KW generator. The hydraulic head
Hydraulic head
Hydraulic head or piezometric head is a specific measurement of water pressure above a geodetic datum. It is usually measured as a water surface elevation, expressed in units of length, at the entrance of a piezometer...
is roughly 495 feet (150.9 m) 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 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 2.2 miles (3.5 km) below the main dam and stores 3140 acre.ft of water. The dam generally releases a constant flow of 2500 cuft/s into the Bighorn.
Spillway
To pass flood waters the Yellowtail Dam is equipped with a tunnel spillway on the left side, capable of handling 92000 cuft/s. The spillway is controlled by a pair of radial gates measuring 25 feet (7.6 m) high and 64.4 feet (19.6 m) long. The dam also has a set of outlet worksOutlet works
A set of outlet works is a device used to release and regulate water flow from a dam. Such devices usually consist of one or more pipes or tunnels through the embankment of the dam, directing water usually under high pressure to the river downstream...
that can discharge up to 2500 cuft/s.
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 a 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
Hoover Dam
Hoover Dam, once known as Boulder Dam, is a concrete arch-gravity dam in the Black Canyon of the Colorado River, on the border between the US states of Arizona and Nevada. It was constructed between 1931 and 1936 during the Great Depression and was dedicated on September 30, 1935, by President...
, Glen Canyon
Glen Canyon Dam
Glen Canyon Dam is a concrete arch dam on the Colorado River in northern Arizona in the United States, just north of Page. The dam was built to provide hydroelectricity and flow regulation from the upper Colorado River Basin to the lower. Its reservoir is called Lake Powell, and is the second...
and Flaming Gorge
Flaming Gorge Dam
The Flaming Gorge Dam is a concrete thin-arch dam in the Flaming Gorge of the Green River, a major tributary of the Colorado River, in the U.S. state of Utah. One of the largest dams in the American West, Flaming Gorge Dam forms the Flaming Gorge Reservoir, which extends into southern Wyoming,...
that would follow severe floods in 1983 in the Colorado River
Colorado River
The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...
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 troutTrout
Trout is the name for a number of species of freshwater and saltwater fish belonging to the Salmoninae subfamily of the family Salmonidae. Salmon belong to the same family as trout. Most salmon species spend almost all their lives in salt water...
fisheries in the United States in the slightly more than 110 miles (177 km) of river downstream. However, the dam has significantly changed the native riverine habitat
Riparian zone
A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the fifteen terrestrial biomes of the earth. Plant habitats and communities along the river margins and banks are called riparian vegetation, characterized by...
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 14 inches (35.6 cm), while the record was a 16 pounds (7.3 kg) rainbow trout
Rainbow trout
The rainbow trout is a species of salmonid native to tributaries of the Pacific Ocean in Asia and North America. The steelhead is a sea run rainbow trout usually returning to freshwater to spawn after 2 to 3 years at sea. In other words, rainbow trout and steelhead trout are the same species....
29 inches (73.7 cm) 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 2500 cuft/s to 2000 cuft/s. 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 1500 cuft/s of flow below the dam.