The U.S. Bureau of Reclamation is celebrating the completion of a new spillway at the 28.5-MW Minidoka hydropower plant with a public ceremony May 27.
The plant — located on the Snake River in Idaho — and its Allen E. Inman power plant have been undergoing a four-year rehabilitation that not straightened the spillway, replaced two irrigation headworks.
HydroWorld.com reported that Record Steel and Construction Inc. had been awarded a US$21.32 million contract to perform the work in September 2011 after a record of decision in September 2010 called for the replacement of infrastructure cited in an environmental impact statement on Minidoka Dam.
The dam is an 86-foot-tall zoned earthfill structure that began operating in 1909. Reclamation said concrete of the 2,237-foot-long wood and concrete spillway, stoplog structure piers, and canal headworks has deteriorated to the point where it could fail soon. In addition, the headworks for the canals that run on the north and south sides of the dam show visible signs of deterioration.
The ceremony takes place 10:30 a.m. and will be held in front of the new control gates on the dam’s south side.
“The original Minidoka Dam was one of the earliest and most successful dams built by Reclamation,” Snake River area manager Jerry Gregg said. “Today, it’s a modern structure that will continue to bring prosperity and reliable water supplies to the area.”
The project added 12 radial-controlled control gates and eliminated an aging stop-log water control system. The dam serves the Burley and Minidoka irrigation districts, which together provided 42% of the project’s cost.
“Our construction division is ready to turn over the keys to our dam operators,” Gregg said. “It’s a new spillway that’s ready for operation for another century.”
Completion of the spillway project will allow the reopening of many fishing and wading areas that were closed during construction.
Minidoka Dam is one of six storage facilities on the Snake and Henrys Fork rivers.
Reclamation is also currently overhauling two turbines in the Inman power plant, most recently calling for bids to refurbish the horizontal turbine runners of Units 8 and 9 in December.
More information about the reopening ceremony can be found at USBR’s website.
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