Calahan, located in El Paso County, Colorado, is a privately owned dam designed by the USDA NRCS for irrigation purposes. Completed in 1963, this earth dam stands at a height of 25 feet and has a storage capacity of 679 acre-feet, serving the needs of the surrounding area for fire protection, stock watering, and small fish ponds. The dam spans a length of 1880 feet and has a spillway width of 128 feet to manage potential excess water flow.

Managed by the Colorado Department of Water Resources, Calahan is regulated, inspected, and enforced to ensure its structural integrity and safety. Despite being classified as having low hazard potential, its condition is assessed as fair, with a moderate risk level of 3. The last inspection in September 2018 highlighted the need for regular monitoring and maintenance to uphold its functionality and to mitigate any potential risks associated with its operations.

With a moderate risk assessment and the potential to impact the Fountain River, Calahan serves as a vital resource for water management in the region. Its historical significance, combined with its practical applications, underscores the importance of sustained oversight and maintenance to ensure the continued efficacy of this essential infrastructure in the face of evolving climate conditions and water resource management challenges.