Wyoming’s LaPrele Dam Set for Demolition to Prevent Potential Catastrophe
The historic LaPrele Dam near Douglas, Wyoming, will be demolished before spring runoff in 2025 to avert the risk of catastrophic failure, state officials announced.
Ordered by Wyoming State Engineer Brandon Gebhart and Governor Mark Gordon, the decision follows years of monitoring and a recent inspection revealing a new crack in the 115-year-old structure, as well as worsening structural deficiencies.
Completed in 1909 and towering at 140 feet, LaPrele Dam is the oldest and tallest open-front dam in the United States. Located above Natural Bridge Park, it creates the LaPrele Reservoir, supplying irrigation water to the surrounding areas. However, due to severe structural issues and operational limitations, the dam’s end has come sooner than planned.
The Wyoming State Engineer issued the breach order on Nov. 1, 2024, mandating demolition before spring runoff to mitigate the danger posed by a potential failure during high-flow conditions. The move has been deemed necessary due to the likelihood that spring runoff would exceed the dam’s reduced capacity to handle inflows, posing a risk to downstream life and property.
Governor Gordon commended Gebhart and his team for proactively addressing the situation.
“This decision was not made lightly, and we recognize the impact it will have on those who rely on that water for irrigation,” the Governor said.
Gordon expressed appreciation for the collaboration between local and state entities to prioritize public safety.
In recent years, inspections uncovered worsening issues in the dam’s structure, including significant cracks that have grown over time. As a result, water storage behind the dam has been restricted since 2019. Gebhart explained that currently, “there is little to no water stored, and the outlets are able to pass inflows,” keeping downstream residents safe while the breach is prepared.
The LaPrele Irrigation District, which owns the dam, has pledged to move forward with the replacement project and appreciates the state’s cooperation in addressing the structure’s condition.
“As owners of this high-hazard dam, we are committed to mitigating the threat it poses to life, property, and natural resources downstream,” the district said in a statement.
Though the LaPrele Dam had been scheduled for replacement within the next several years, this decision accelerates the timeline. The district aims to complete the new dam’s design by 2026, with a projected construction finish in 2028.
The Wyoming Department of Transportation (WYDOT) is also closely monitoring the impact of LaPrele Dam’s decommissioning on infrastructure in the area, particularly Interstate 25 and other nearby bridges and underpasses.
“A dam failure could have had major impacts on I-25 and related infrastructure,” said WYDOT Director Darin Westby.
Converse County Commission Chairman Jim Willox, while expressing disappointment over the need to breach the dam, acknowledged the importance of preventing a catastrophic failure, which “would be devastating” to the community and environment.
With input from Jackson Hole News and Guide.
