State digs into sites to replace LaPrele

DOUGLAS — State officials said they are actively looking for a place to build a new LaPrele Dam downstream from the current unsound one.
Exploration is underway on the future location, Wyoming Water Development Project Engineer Chace Tavelli said last week. 
Project consultants have been “making progress on the study. They are in the final stages of what has been a very successful geotechnical drilling program further characterizing the area downstream of the existing dam,” he said.
The 113-year-old LaPrele Dam, built in 1909, sits between Douglas and Glenrock, and is owned by the LaPrele Irrigation District. The oldest and tallest open front dam in the nation, it is located above Ayres Natural Bridge and creates the LaPrele Reservoir about 21 miles outside of Douglas via I-25 and about three miles down Natural Bridge Road. 
Tavelli said that the drilling program “is investigating properties to aid in the design of abutments, foundation and a plunge pool for a potential downstream dam option as well as investigating potential aggregate sources.” 
Former WWDC Director Brandon Gebhart said more than a year ago that the dam was at the end of its lifespan. 
The irrigation district applied to the Wyoming Water Development Commission to start a level one master plan study in 2018. The studies on the dam escalated incrementally because “if the dam were to fail, it would be catastrophic,” he said. 
Costs on rebuilding the dam or building a new one have been all over the board, ranging from $30 million to more than $100 million, but officials are reluctant to nail down a price tag given how the project keeps changing. 
The historic dam contains serious documented structural damages, and if it does fail could take out Ayres Natural Bridge & the park in just minutes before flooding ranches and energy industrial sites before reaching Douglas. 
The state is taking the threat of the dam’s catastrophic failure seriously, as well as the need for water for surrounding ranchers, other agricultural uses and landowners. 
Through further and deeper analysis, WWDC escalated the issue, going to the Legislature to see if it could obtain help in funding the cost of a new dam. 
It’s been a hurry-up-and-wait scenario since then, but Tavelli said Gov. Mark Gordon’s office “recently received a response letter from Bureau of Reclamation (BOR) Commissioner (Camille) Touton relative to Carey’s Act Dam language in the Infrastructure Investment and Jobs Act (IIJA).” 
“The letter to the governor states that BOR has determined the LaPrele Dam meets the criteria set forth in the IIJA, and that the funding is non-reimbursable for work performed at LaPrele or other Carey Act dams with IIJA funding. In other words, BOR would not be seeking repayment (for monies received for a new LaPrele dam), which is very positive news,” he said. 
Tavelli said Reclamation and the WWDC are coordinating to begin the financial assistance application process. State engineers have mandated the dam’s water level stay at or below 5,475 feet, which equates to being about 60 percent filled. 
The lower level of water minimizes stress on the dam for now, they said. 
LaPrele Irrigation District President Colt Rodeman has previously stated that people at Ayres Natural Bridge Park, just a short distance downstream of the structure, would have just 10 minutes to evacuate before the area is flooded. He said approximately 75 people would be at immediate risk between the Ayres Natural Bridge State Park and Douglas.
 
This story was published on Nov. 2, 2022.