Members of the LaPrele Irrigation District met with Converse County Commissioners Nov. 6, to update them on the progress of the ongoing LaPrele Dam rehabilitation project.
RESPEC Watershed Management Program Manager Peter Rausch, of Rapid City, S.D., reported that a limited visual inspection of the LaPrele Dam was performed by HDR Engineering, Inc. on Sept. 24, as part of the ongoing LaPrele Irrigation District Rehabilitation, Level II Study.
During the inspection, “multiple cracks and the deterioration of concrete were identified in features of the dam near the west side, specifically including the western-most buttress (buttress no. 17), the decommissioned spillway and the west abutment,” according to a Nov. 5 external memorandum distributed at the commissioners’ meeting.
To err on the side of caution, HDR’s engineers have recommended that the reservoir’s water surface elevation be limited to 5,475 feet, although as of the date of the memo, the level was at 5,463, 12 feet below the recommended limit, officials said.
Rausch said that their project team is working with the Wyoming Water Development Office to define the next steps regarding the dam.
“Our top priority is to understand the extent and severity of the structural issues. From there, we want to help you and the irrigation district manage potential risks and develop solutions,” he wrote.
LaPrele Irrigation District President Colt Rodeman wants residents to know that there’s absolutely no threat regarding the dam, though. It’s intact, and there’s no seepage or leaks.
“There is no imminent danger at all, of any kind,” Rodeman said.
“The structural indifference is on the very outside of buttress 17. There’s no water seeping, there’s no leaking anywhere. The face isn’t cracked. I want to be clear that there is no threat or danger (from the dam),” he said last week.
LaPrele Dam is located above Ayres Natural Bridge on LaPrele Reservoir about 21 miles out of Douglas via I-25 and Natural Bridge Road. It is privately owned by the shareholders of the LaPrele Irrigation District.
Rausch told commissioners more tests will be performed including an inspection of all buttresses and limited core sampling from the concrete, to determine the strength of the dam.
But, a date hasn’t been set yet for the next stage of inspections and testing, Rodeman said, nor has the cost of the project been determined at this point.
“We don’t have a definite date, but we’ll try to do it sooner rather than later,” he confirmed.
Rodeman told commissioners that irrigation from the dam may start earlier than normal next spring, but it’s dependent on several factors.
“Maybe. We don’t know where we’re going to be at for sure by then. It depends upon a lot of things. We usually start (irrigation) May 1. We won’t know for certain until we get there,” Rodeman said days afterward.
The irrigation district is responsible for the safe operation and the dam’s maintenance. The dam is also periodically inspected by the State Engineer’s Office.
The dam was built in 1909 for irrigation purposes, according to Converse County records. LaPrele Creek is the source of water for the reservoir behind the dam.
Rodeman said the LaPrele Irrigation District will hold a public meeting at the Converse County Library Dec. 9 at 7 p.m., to bring the public and shareholders up-to-date on the dam’s rehabilitation project.
“We have notified all of the shareholders by either email or the post office. If people have any questions they can get a hold of me. I owe it to all of the shareholders and the converse county commissioners ... we’ve had the dam for 100 years, I want to see that we have it for another 100 years,” he said.