Pathfinder Dam

Last updated
Pathfinder Dam
Pathfinder Dam - Wyoming.jpg
Pathfinder Dam
Location Natrona County, Wyoming, USA
Coordinates 42°28′05″N106°51′14″W / 42.46806°N 106.85389°W / 42.46806; -106.85389 Coordinates: 42°28′05″N106°51′14″W / 42.46806°N 106.85389°W / 42.46806; -106.85389
Construction began1905
Opening date1909
Operator(s) U.S. Bureau of Reclamation
Dam and spillways
Type of dam Cyclopean masonry gravity arch
Impounds North Platte River
Height214 feet (65 m)
Length432 feet (132 m)
Width (crest)10.5 feet (3.2 m)
Width (base)96.5 feet (29.4 m)
Dam volume65,700 cu yd (50,200 m3)
Spillway typeUncontrolled natural channel
Spillway capacity33,940 cu ft/s (961 m3/s)
CreatesPathfinder Reservoir
Total capacity1,016,500 acre feet (1.2538 km3)
Catchment area 14,600 sq mi (38,000 km2)
Power Station
Hydraulic head 300 ft (91 m)
Turbines 2 x 33.4 MW Francis-type at Fremont Canyon Powerplant
Installed capacity 66.8 MW
Annual generation 172,606,300 KWh (2007)
Pathfinder Dam
NRHP reference No. 71000888 [1]
Added to NRHPAugust 12, 1971

Pathfinder Dam is a masonry dam, located on the North Platte River, approximately 47 miles (76 km) southwest of Casper, Wyoming. It was originally constructed between 1905 and 1909 as part of the North Platte Project and has been modified several times since then. It is included on the National Register of Historic Places. Construction of the dam created Pathfinder Reservoir which provides water storage for 226,000 acres (910 km2) of irrigation in Wyoming and Nebraska. [2] The dam is named for General John Charles Fremont, who had explored the area in 1842 and was nicknamed the "Pathfinder of the West."



Pathfinder Dam is composed of granite blocks, quarried from the same stone that forms the river's canyon. With Buffalo Bill Dam, its contemporary, Pathfinder Dam was intended to irrigate semi-arid lands in Wyoming. Buffalo Bill Dam, however, is of concrete construction, owing to its location within 7 miles (11 km) from the railroad, while Pathfinder Dam is about 45 miles (72 km) from the nearest railroad. Freight took at least three days to cover the distance, and once took 76 days. [3] Transportation of cement in barrels was not feasible by horse-drawn wagon, so the dam was built of quarried stone. The dam was faced with stones between 24 inches (61 cm) and 36 inches (91 cm) thick, laid in a 2-inch (5.1 cm) thick mortar bed. Between these facings was a core of irregularly-shaped granite blocks of up to ten tons in weight, bedded in mortar and quarry tailings. The diversion tunnel was adapted to become the dam's outlet works. Construction costs were $2.5 million in 1909. [4] An auxiliary dike, 38 feet (12 m) high, extends to the south of the dam. It is an earthfill structure with a concrete corewall. A natural channel was enlarged and straightened to form an uncontrolled spillway on the north side of the dam. [2]

The original diversion tunnel became the north outlet works, abandoned and sealed in 1958 with bulkheads. From 1958 the tunnel was modified to feed the power outlet works, an 18 feet (5.5 m) tunnel extending 3 miles (4.8 km) to the Fremont Canyon Powerplant at the upper end of Alcova Reservoir. [3] The Fremont Canyon Powerplant has a capacity of 66.8 MW with two turbines, upgraded from 48 MW between 1986 and 1990. A low-flow outlet was completed at the dam in 1997 to allow water flow in the four river miles between the dam and the powerplant. [5]


Pathfinder Dam overflowing

In 1902 plans were advanced to dam the Sweetwater River at a narrow point known as Devil's Gate. A more ambitious plan was proposed in 1903 by the newly established Bureau of Reclamation to dam a site below the confluence of the Sweetwater and the North Platte. [4] The dam's design was carried out by George Y. Wisner of the Reclamation Service, with consulting engineer Edgar T. Wheeler. [6] Exploratory drilling was started in 1903, and a contract for a 480-foot (150 m) long diversion tunnel was let in 1905. Bidding for the dam construction contract was plagued with delays; the initial contractor withdrew, citing bidding errors. Eventually, the construction contract was awarded to the Geddis and Seerie Stone Company of Denver, for an initial sum of $482,000, later to rise to $626,523.52. Difficulties with the construction of an upstream cofferdam, created by the contractor's improper blasting of loose rock from the canyon walls, led to the first delays. Foundation work on the dam started in January 1906, with the foundation set only 10 feet (3.0 m) deep. [3]

After delays caused by flood waters, the dam was completed on June 14, 1909. However, unusual summer rains filled the reservoir, overtaxed the spillways and threatened to overtop the unfinished auxiliary dike south of the dam, possibly allowing the river to cut a new, lower channel and potentially leaving the damsite dry. Explosive charges were placed in the crest of the main dam, to be used if the overflow occurred, thus keeping the lowest point at the dam. The dike held and the charges were not needed, but did have to be removed by explosives experts in 1949. [4] An auxiliary dike was built at the location in 1910 to develop the reservoir's full capacity. The potential overtopping gave rise to sensational stories in Denver newspapers and caused annual nervousness in Casper downstream for a number of years thereafter. [3] The Fremont Canyon Powerplant was built between 1958 and 1961, part of the Glendo Unit of the Pick–Sloan Missouri Basin Project. [5]

The reservoir has suffered from sedimentation, as all dams do, which leads to reduced capacity and leading to a 1995 proposal to add between 2 feet (61 cm) and 2.5 feet (76 cm) to the top of the dam to add storage capacity. [3]

The Pathfinder Interpretive Center is a small museum located in the former damkeeper's residence near the dam. Pathfinder National Wildlife Refuge encompasses portions of the reservoir. There are five campgrounds and a marina on the reservoir. A suspension footbridge crosses the river below the dam. [7] Pathfinder Dam was placed on the National Register of Historic Places on August 12, 1971. [1] In 2015, the dam was included in a historic district encompassing the dam itself, its operating facilities, and the archaeological remains of its construction camp. [8] [9]

The reservoir has overflowed in 1984, 2010 and 2011, and 2016 with overflow water forcing a channel to the immediate north of the dam. [10] [11]

Pathfinder Dam spillway in June 2010

See also

Related Research Articles

Glen Canyon Dam Dam in Coconino County, Arizona

Glen Canyon Dam is a concrete arch-gravity dam on the Colorado River in northern Arizona, United States, near the town of Page. The 710-foot (220 m) high dam was built by the U.S. Bureau of Reclamation (USBR) from 1956 to 1966 and forms Lake Powell, one of the largest man-made reservoirs in the U.S. with a capacity of 27 million acre feet (33 km3). The dam is named for Glen Canyon, a series of deep sandstone gorges now flooded by the reservoir; Lake Powell is named for John Wesley Powell, who in 1869 led the first expedition to traverse the Colorado's Grand Canyon by boat.

North Platte River River in the Western United States

The North Platte River is a major tributary of the Platte River and is approximately 716 miles (1,152 km) long, counting its many curves. In a straight line, it travels about 550 miles (890 km), along its course through the U.S. states of Colorado, Wyoming, and Nebraska.

Colorado-Big Thompson Project

The Colorado-Big Thompson Project is a federal water diversion project in Colorado designed to collect West Slope mountain water from the headwaters of the Colorado River and divert it to Colorado's Front Range and plains. In Colorado, approximately 80% of the state's precipitation falls on the West Slope, in the Rocky Mountains, while around 80% of the state's growing population lives along the East Slope, between the cities of Fort Collins and Pueblo.

Flaming Gorge Dam Concrete thin-arch dam on the Green River in northern Utah, United States

Flaming Gorge Dam is a concrete thin-arch dam on the Green River, a major tributary of the Colorado River, in northern Utah in the United States. 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.

Shoshone Project

The Shoshone Project is an irrigation project in the U.S. state of Wyoming. The project provides irrigation for approximately 107,000 acres (430 km2) of crops in the Big Horn Basin, fulfilling the vision of local resident and developer Buffalo Bill Cody, who hoped to make the semi-arid basin into agricultural land. Buffalo Bill Dam on the Shoshone River impounds water for the project in Buffalo Bill Reservoir. In addition to its role in irrigation, the project provides flood control on the Shoshone and generates power, using the 350-foot (110 m) height of Buffalo Bill Dam, once a world record, and the considerable fall of the river through Shoshone Canyon to generate hydroelectric power. Chief crops in the Big Horn Basin are sugar beets, alfalfa, barley, oats, corn and beans.

Blue Mesa Dam Dam in Cimarron, Gunnison County, Colorado, USA

Blue Mesa Dam is a 390-foot-tall (120 m) zoned earthfill dam on the Gunnison River in Colorado. It creates Blue Mesa Reservoir, and is within Curecanti National Recreation Area just before the river enters the Black Canyon of the Gunnison. The dam is upstream of the Morrow Point Dam. Blue Mesa Dam and reservoir are part of the Bureau of Reclamation's Wayne N. Aspinall Unit of the Colorado River Storage Project, which retains the waters of the Colorado River and its tributaries for agricultural and municipal use in the American Southwest. The dam's primary purpose is hydroelectric power generation. State Highway 92 passes over the top of the dam. Blue Mesa Dam houses two turbine generators and produces an average of 264,329,000 kilowatt-hours each year.

Morrow Point Dam Dam in Cimarron, Gunnison County, Colorado, USA

Morrow Point Dam is a 468-foot-tall (143 m) concrete double-arch dam on the Gunnison River located in Colorado, the first dam of its type built by the U.S. Bureau of Reclamation. Located in the upper Black Canyon of the Gunnison, it creates Morrow Point Reservoir, and is within the National Park Service-operated Curecanti National Recreation Area. The dam is between the Blue Mesa Dam (upstream) and the Crystal Dam (downstream). Morrow Point Dam and reservoir are part of the Bureau of Reclamation's Wayne N. Aspinall Unit of the Colorado River Storage Project, which retains the waters of the Colorado River and its tributaries for agricultural and municipal use in the American Southwest. The dam's primary purpose is hydroelectric power generation.

Crystal Dam Dam in Cimarron, Gunnison County, Colorado, USA

Crystal Dam is a 323-foot-tall (98 m), double-curvature, concrete, thin arch dam located 6 miles downstream from Morrow Point Dam on the Gunnison River in Colorado, United States. Crystal Dam is the newest of the three dams in Curecanti National Recreation Area; construction on the dam was finished in 1976. The dam impounds Crystal Reservoir. Crystal Dam and Reservoir are part of the Bureau of Reclamation's Wayne N. Aspinall Unit of the Colorado River Storage Project, which retains the waters of the Gunnison River and its tributaries for agricultural and municipal use in the American Southwest. The dam's primary purpose is hydroelectric power generation.

Yellowtail Dam Dam in Big Horn County, Montana

Yellowtail Dam is a dam across the Bighorn River in south central 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.

Auburn Dam Dam in Near Auburn, California

Auburn Dam was a proposed concrete arch dam on the North Fork of the American River east of the town of Auburn, California, in the United States, on the border of Placer and El Dorado Counties. Slated to be completed in the 1970s by the U.S. Bureau of Reclamation, it would have been the tallest concrete dam in California and one of the tallest in the United States, at a height of 680 feet (210 m) and storing 2,300,000 acre feet (2.8 km3) of water. Straddling a gorge downstream of the confluence of the North and Middle Forks of the American River and upstream of Folsom Lake, it would have regulated water flow and provided flood control in the American River basin as part of Reclamation's immense Central Valley Project.

Buffalo Bill Dam Dam in Park County, Wyoming, US

Buffalo Bill Dam is a concrete arch-gravity dam on the Shoshone River in the U.S. state of Wyoming. It is named after the famous Wild West figure William "Buffalo Bill" Cody, who founded the nearby town of Cody and owned much of the land now covered by the reservoir formed by its construction. The dam is part of the Shoshone Project, successor to several visionary schemes promoted by Cody to irrigate the Bighorn Basin and turn it from a semi-arid sagebrush-covered plain to productive agricultural land. Known at the time of its construction as Shoshone Dam, it was renamed in 1946 to honor Cody.

Rio Grande Project

The Rio Grande Project is a United States Bureau of Reclamation irrigation, hydroelectricity, flood control, and interbasin water transfer project serving the upper Rio Grande basin in the southwestern United States. The project irrigates 193,000 acres (780 km2) along the river in the states of New Mexico and Texas. Approximately 60 percent of this land is in New Mexico. Some water is also allotted to Mexico to irrigate some 25,000 acres (100 km2) on the south side of the river. The project was authorized in 1905, but its final features were not implemented until the early 1950s.

Risks to the Glen Canyon Dam

Glen Canyon Dam, a concrete arch dam on the Colorado River in the American state of Arizona, is viewed as carrying a large amount of risk, most notably due to siltation. The Colorado and San Juan rivers deposit large volumes of silt into Lake Powell, slowly decreasing its capacity. The sediment will eventually build up against the dam and could affect its safe operation and lead to its failure.

Guernsey Dam Dam in Platte County, Wyoming, USA

Guernsey Dam is an earthfill dam on the North Platte River in Platte County in the U.S. State of Wyoming. The dam creates Guernsey Reservoir, the last of the 5 major reservoirs on the North Platte River in Wyoming. The dam contains a hydroelectric plant capable of 6.4 megawatts of electricity. The total capacity of the reservoir is 71,040 acre feet (87,630,000 m3) of water which is used mainly for irrigation. Morrison-Knudsen and Utah Construction Company constructed Guernsey Dam and the hydroelectric plant as part of the North Platte Project to provide irrigation to eastern Wyoming and western Nebraska. Guernsey helps control the river flow and stores water released from the project's primary storage upstream at Pathfinder Reservoir. About 8 miles (13 km) downstream of the dam the Whalen Diversion Dam diverts water into the Fort Laramie and Interstate Canals that service farms in Wyoming and Nebraska.

North Platte Project

The North Platte Project is an irrigation project in the U.S. states of Wyoming and Nebraska. The project provides irrigation service to about 335,000 acres (1,360 km2). The primary water storage for the project is in Pathfinder Reservoir in Wyoming. Downstream, Guernsey Dam manages river flow and provides secondary storage for water released from Pathfinder. Near Fort Laramie the Whalen Diversion Dam diverts water into Fort Laramie Canal and Interstate Canal which distribute water to farms in Wyoming and Nebraska.

Seminoe Dam Dam in Carbon County, Wyoming

Seminoe Dam is a concrete thick-arch dam on the North Platte River in the U.S. state of Wyoming. The dam stores water for irrigation and hydroelectricity generation, and is owned and operated by the U.S. Bureau of Reclamation. It is the uppermost dam on the North Platte River and is located directly upstream from the Kortes Dam. It lies in a narrow, isolated canyon formed by the North Platte cutting through the Seminoe Mountains about 40 miles (64 km) northeast of Rawlins. The 295-foot (90 m) dam forms Seminoe Reservoir, which covers more than 20,000 acres (8,100 ha) when full. Seminoe State Park is adjacent to the reservoir. The small village of Seminoe Dam abuts the dam and reservoir, and provides residence for the dam attendants and park services personnel.

Boysen Dam Dam in Fremont County, Wyoming

The Boysen Dam is a rockfill dam on the Wind River in the U.S. state of Wyoming. The dam lies at the head of Wind River Canyon through the Owl Creek Mountains in western Wyoming and creates Boysen Reservoir. It is owned by the U.S. Bureau of Reclamation and furnishes irrigation water supply to the Bighorn Basin as well as providing flood control and hydroelectric power.

Alcova Dam Dam in Natrona County, Wyoming, USA

Alcova Dam is a 265-foot (81 m) tall zoned earthfill dam in central Wyoming, built in 1935-38 on the North Platte River and operated by the U.S. Bureau of Reclamation for water storage and hydroelectric power generation. The dam was built as part of the Kendrick Project, formerly the Casper-Alcova Project, whose central features are Alcova and Seminoe dams.

Heron Dam Dam in Rio Arriba County, New Mexico

Heron Dam is a storage dam Rio Arriba County, in northern New Mexico in the southwestern United States, just north of the El Vado Dam. It is owned and operated by the United States Bureau of Reclamation. The dam is about 9 miles west of the town of Tierra Amarilla.


  1. 1 2 "National Register Information System". National Register of Historic Places . National Park Service. March 13, 2009.
  2. 1 2 "North Platte Project". U.S. Bureau of Reclamation. Retrieved 17 May 2011.
  3. 1 2 3 4 5 Autobee, Robert (1996). "North Platte Project" (PDF). U.S. Bureau of Reclamation.
  4. 1 2 3 Frost, Nedward (1971). "National Register of Historic Places — Inventory-Nomination Form: Pathfinder Dam". National Park Service. Retrieved 16 May 2011.
  5. 1 2 "Fremont Canyon Powerplant". U.S. Bureau of Reclamation. Retrieved 17 May 2011.
  6. Scott, Gregg A. (September 2002). "Concrete Dam Evolution: The Bureau of Reclamation's Contributions to 2002" (PDF). Historical Essays from the Centennial Symposium. U.S. Bureau of Reclamation. p. 4. Archived from the original (PDF) on 2012-01-28. Retrieved 2011-06-03.
  7. "Pathfinder Reservoir". Natrona County. Retrieved 17 May 2011.
  8. "Bureau of Reclamations Section 3 Progress Report 2011-13" (PDF). United States Government. Retrieved 2015-07-03.
  9. "Weekly List of Actions Taken, 6/15/15 to 6/26/15". National Park Service. Retrieved 2015-07-03.