LaPrele Dam Ordered to be Breached

Following ongoing monitoring and a recent thorough inspection of the condition of LaPrele Dam, Wyoming State Engineer Brandon Gebhart issued an order to breach the 115-year-old dam. The recent discovery of a large, new crack above the dam’s outlet works, the deterioration of previously identified structural deficiencies, and the operational limitations of the existing dam led to the decision.

“I want to commend the State Engineer and his staff for recognizing the significant risks of a potential dam failure and proactively addressing them before a disaster occurred,” Governor Gordon said. “This decision was not made lightly, and we recognize the impact this will have on those who rely on that water for irrigation.”

The LaPrele Dam is owned and operated by the LaPrele Irrigation District and located 20 miles west of Douglas. The deteriorating conditions of the dam had been identified and monitored by the State Engineer’s Office, the District, and the Wyoming Water Development Office, eventually leading the State Engineer to issue orders restricting water storage behind the dam in 2019. Currently there is little to no water behind the dam, and the dam’s outlet works are completely open and passing all inflows into LaPrele Creek.

“This dam has significant structural deficiencies and has exceeded its useful life,” Gebhart said. “Due to preemptive actions already taken, there is currently no risk or danger to the public downstream because there is little to no water stored and the outlets are able to pass inflows to prevent new storage. However, continued use of the dam to store water could cause catastrophic failure, which poses a threat to life and property. These threats need to be mitigated before the spring runoff, when flows are expected to exceed the dam’s ability to pass inflows.”

“I greatly appreciate the collaboration of my staff, the District, the Water Development Office and their technical representatives all working together to identify and address this significant threat before something very catastrophic occurred.” 

Given the age and condition of the structure, LaPrele Dam was already scheduled for replacement in the coming years.  Planning for the replacement is underway. These plans include demolition of the dam which was set to occur as part of the replacement project. The Breach Order now requires the demolition to be completed prior to the upcoming spring runoff season.

“I appreciate the State Engineer's foresight and agency expertise to detect a risk and prevent failure. A dam failure could have had major impacts to Interstate 25 and other transportation infrastructure like bridges and underpasses,” WYDOT Director Darin Westby said. “We will be monitoring the impacts of the decommissioning on all impacted WYDOT infrastructure.”

In a statement, the LaPrele Irrigation District expressed its appreciation for the collaborative efforts the state has undertaken to address the dam’s issues.

“The LaPrele Irrigation District has been working actively with our consultants and State Agencies to evaluate this new issue ever since it was brought to light. As members of the Board, we take the responsibility of safeguarding the District shareholders' interests very seriously, and we have advocated accordingly throughout this process. Their livelihoods and ours depend on the LaPrele Reservoir. We also hold paramount our responsibility as owners of this high hazard dam to mitigate the threat it currently poses to life, property, and natural resources downstream.”

“We are grateful for the support and collaboration of the State Engineer's Office and the Water Development Office in addressing the issue. We intend to comply with the State's Order, and we continue our unwavering commitment to replacing the LaPrele Dam with a renewed sense of urgency.”

The State Engineer’s order may be found here.