The dam's design was carried out by George Y. Wisner of the Reclamation Service, with consulting engineer Edgar T. Wheeler. Exploratory drilling was started in 1903, and a contract for a 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 deep. 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. 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. The Fremont Canyon Powerplant was built between 1958 and 1961, part of the Glendo Unit of the Pick–Sloan Missouri Basin Project. The reservoir has suffered from siltation, leading to a 1995 proposal to add between and to the top of the dam to add storage capacity. 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. Pathfinder Dam was placed on the National Register of Historic Places on August 12, 1971. 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. The reservoir has overflowed in 1984, 2010 and 2011, with overflow water forcing a channel to the immediate north of the dam.