Lawmakers on the Joint Appropriations Committee were briefed last week on plans to replace the failing LaPrele Dam about 20 miles west of Douglas.

Jason Mead is the director of the state Water Development Office. He told the committee the current cost estimate, with about 30 percent of design work complete, is $137 million.

“But with the unknowns and the design that needs to be completed, they've given us a range of anywhere from $116 million to $178 million,” he added.

Mead said costs are likely to increase given the quick timeframe to shore up the 115-year-old structure ahead of anticipated spring runoff, which could cause a catastrophic failure and send a torrent of water downstream toward highway infrastructure, including Interstate 25, bridges and underpasses, and Ayres Natural Bridge Park.

More recent inspections revealed even worse than expected cracks and decay.

“There was a sheer crack on one of the buttresses in the middle that basically went from the slab – so very high up – all the way down to the foundation, which the engineers determined that it was actively failing more or less,” Mead said.

He said that led to the order to breach the dam by Apr. 1.

The state engineer began issuing orders in 2019 to restrict water storage behind the dam due to deteriorating conditions. “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,” according to a Nov. 1 press release from the governor’s office.

Lawmakers set aside $30 million for general dam reconstruction in 2022. The state engineer’s office is hoping for another $100 million from the Inflation Reduction Act.

Mead estimated a nearly $60 million shortfall if the project comes in at the higher end.

The dam provides water for over 100 shareholders in the LaPrele Irrigation District.