By Josh Margolis
HAVRE, Mont. (NMB) – The Bureau of Reclamation is moving forward with a project to fix deficiencies with Fresno Dam.
Project Manager Steve Darlinton says this modification will mitigate any deficiencies in the dam from historic foundation settlement of up to 10 feet.
“This will be done by placing a sand and gravel filter, along with a trench along the downstream face to intercept any seepage that may come through the embankment or the foundation. It should be expressed that while Reclamation is moving forward with modifying the dam for this issue, there is no immediate threat to the public. Rather, the possibility of a failure event has risen above Reclamation’s public protection guidelines for taking action.”
Darlinton has previously said that potential failure is currently about a 1 in 5,000 chance-per-year, which places it below the 1 in 10,000 chance-per-year cutoff that Reclamation uses when deciding whether projects are necessary.
The entire project has an estimated cost of $71 million. The federal government will be paying 85 percent of the costs, while water users will have to pay the other 15 percent, which is estimated at around $10.65 million. That amount can be paid over 50 years and without interest.
Designs on the project are expected to be completed in early 2022. The Bureau will then go about selecting a contractor, with on-site work scheduled to start in early 2023 and conclude in 2026.
Darlinton says impacts to irrigators and the fishery during the project will be minimal.
“As far as the irrigators go, there’s kind of two impacts. There’s actual water supply issues, and then there’s costs. So from a water supply perspective, the proposed modifications should not have a significant effect. This alternative was chosen because it does not require significant long-term drawdown of the reservoir for construction. Rather, it requires a drawdown to roughly 2,555 feet, which is about 20 feet below full pool or the spillway elevation. That will coincide with the end of irrigation season for tying the sand filter into the spillway wall. And then as far as the fishery and recreation goes, it’s pretty similar to the irrigation. The proposed drawdown is well within traditional operations and significant impacts to recreation are not anticipated.”
Public meetings are expected to be held across the Hi-Line in October and November.
The public comment period on the environmental assessment runs through September 10th.
