Anchor Dam is a dam in

Hot Springs County, Wyoming Hot Springs County is a County (United States), county in the U.S. state of Wyoming. As of the 2020 United States Census, the population was 4,696, making it the second-least populous county in Wyoming. Its county seat is Thermopolis, Wyoming, T ...

, about west of

Thermopolis Thermopolis is the county seat and largest town in Hot Springs County, Wyoming, United States. As of the 2020 U.S. Census, the town population was 2,725. Thermopolis is Greek for "hot city." It is home to numerous natural hot springs, in which m ...

. The concrete thin-arch dam was completed in 1960 by the

United States 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 ...

as a water storage project. The -high dam structure impounds the water of the South Fork of Owl Creek, with the spillway as designed as a central overflow. During construction, the discovery of solution cavities in the bedrock forced the re-positioning and re-configuration of the dam, causing delays and added expense. The same

karst Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ro ...

solution cavities prevented Anchor Reservoir from filling its design capacity of . It has never been full. More than 50 sinkholes had been identified in the underlying

Chugwater Formation The Chugwater Formation is a mapped bedrock unit consisting primarily of red sandstone, in the states of Wyoming, Montana, and Colorado in the United States. It is recognized as a geologic formation in Colorado and Montana, but as a Group (set of ...

geology of the reservoir basin, with at least one of them in diameter and deep. The site's lack of "hydraulic integrity" was well known to Bureau scientists before and during construction. The reservoir fills enough to provide some irrigation benefit through July and August of each season. It is operated by the local Owl Creek Irrigation District.

References

{{authority control Buildings and structures in Hot Springs County, Wyoming Dams in Wyoming Reservoirs in Wyoming United States Bureau of Reclamation dams Arch dams Dams completed in 1960 1960 establishments in Wyoming Landforms of Hot Springs County, Wyoming