Pipestem Dam & Lake, North Dakota

Pipestem Dam was constructed for flood damage reduction, fish and wildlife enhancement, and recreation. Construction of the dam began in June 1971, and was completed in 1973. The dam measures approximately 4,000 feet in length, with a maximum height of 107.5 feet from the stream bed to the top of the dam. Also nearby is the Jamestown Dam and Reservoir, which is operated by the U.S. Bureau of Reclamation. 

The River Basin Balancer Game offers insight into an inland waterway and a system of reservoirs, which are operated with a goal for serving each of the benefits, flood control, navigation, hydropower, irrigation, water supply, recreation, fish and wildlife, and water quality, for which many USACE reservoirs are authorized and constructed. Users can take charge of river operations and experience the unique challenges presented when managing reservoir operations in a variety of weather conditions across a geographically diverse basin.

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Description

Location: North of Jamestown, N.D. on Pipestem Creek,

Pipestem Dam and Reservoir is owned, operated, and maintained by the U.S. Army Corps of Engineers. The dam includes an earthen embankment across the river, and a gated outlet structure through the embankment that releases stored water during normal operations for recreation and to support fish and wildlife. Water also can flow through an earthen spillway if the need to release water exceeds the capacity of the outlet structure.

Completed in 1973 on Pipestem Creek, it was the second of two dams built by USACE and the Bureau of Reclamation to reduce impacts from flooding on life safety and property in Jamestown, N.D. Water storage and its release from Pipestem Lake are coordinated with Reclamation who owns Jamestown Dam and Reservoir, about 6 miles east and also in the James River Basin.

Late summer landscape on the Pipestem Dam embankment in 2022.
The outlet tunnel through the Pipestem Dam embankment released a record flow of 1420 cubic feet of water per second in April 2009. The outlet is designed to release up to 2,300. (One cubic foot of water is equal to 7.5 gallons.)

Managing flow to reduce risk

During periods of high runoff, most often during extreme storms when rain or snowmelt fill the reservoir, the outlet structure can release up to 2,300 cubic feet of water per second. (One cubic foot of water is equal to 7.5 gallons.) The Jamestown Dam outlet can release just over 2,700 cfs.  For perspective, the record water release in 2009 through the outlet structures at Pipestem and Jamestown dams were 1,420 and 1,807 cubic feet of water per second, respectively, for a combined 3227 cfs release flow.

The Pipestem spillway has never been needed but it is designed to pass more than 56,000 cfs of water if necessary. Even if streams and rivers below the dams reach or exceed their capacity, water can flow through the spillway to reduce the possibility of water flowing over the dam that can lead to dam failure, or breach. A breach would allow the water stored behind the dam to flow uncontrolled, further intensifying downstream flooding. This would impact critical infrastructure and downstream levee systems and put thousands of lives at risk in Jamestown and further downstream in the James River Basin. 

Pipestem Dam continues to reliably reduce floods, but it alone, or in conjunction with Jamestown Dam, cannot eliminate the risk of flooding.

Maintaining the dam over time

As part of its Dam Safety Program, USACE Omaha District conducts detailed engineering analyses to understand and reduce risks to the public, property, and the environment   to the extent possible. Standards and practices that guide the Dam Safety Program are continually updated to improve the maintenance and operation of USACE dams to ensure they reliably serve their original purposes. Dam safety engineers across federal and state agencies also share information about the performance of flood reduction structures built over many decades and they use more precise, modern technologies and apply up-to-date science to reduce flood risk more effectively.

During flooding in 2009, the spillway on Cottonwood Creek Dam south of Lamoure, ND, experienced severe erosion. (The dam is owned by the North Dakota Game & Fish Department.) USACE dam safety experts evaluated Cottonwood Creek’s spillway, which has similar geological materials and geometry to Pipestem’s spillway. Using tools and information developed since Pipestem’s original design in the late 1960s, USACE better understands the dam’s ability to withstand erosion. From this, it was determined that under extreme flood conditions the original spillway, with its highly erodible sands and gravels, presents an unacceptable risk of progressive spillway erosion that could lead to a spillway breach and the uncontrolled release of water.

Taking action on current concerns

Omaha District evaluated several options to address the threat of spillway erosion. The selected plan will prevent the progression of erosion that could lead to a spillway breach. In addition to studying the issues with the spillway, a team of structural engineers, geologists, and hydrologists evaluated additional ways to increase overall performance at the dam including the stability of slopes located along or near the spillway. The design of the multi-stage construction project is now complete and USACE anticipates on-site construction of a combination of spillway improvements to begin in spring 2023.