WEISER, Idaho — The moment of decision is nearing on whether to move forward with a new dam and reservoir that could benefit thousands of farmers in southern Idaho.
The proposed Galloway dam would add about 700,000 acre-feet of reservoir storage capacity on the Weiser River.
Officially called the Weiser-Galloway Project, the dam and reservoir would be built on the Weiser River near its confluence with the Snake River, about 13.5 miles from the city of Weiser.
It would have the peak capacity to generate 40-60 megawatts of hydropower, which would help pay for the estimated $500 million cost of the project.
Idaho Water Resource Board Chairman Roger Chase said the board expects to make a decision on the project in the next several months.
Chase said the board has to weigh whether the benefits of the project match the cost.
“Finding more storage is a high priority for (the board),” he said. “Galloway is a great site. The money issue is what’s driving it now. Can it pay for itself?”
The Idaho Department of Water Resources and U.S. Army Corps of Engineers have studied the project.
Two additional studies are still outstanding, and the IDWR plans to have those completed and provide the results to the water board and public in the next few months, said Cynthia Bridge Clark, a staff engineer in the IDWR’s water planning section.
One of those studies is an operational analysis of what the potential benefits of the project would be “and whether they are substantial enough to advance a project of that scale,” she said.
The other study looked at whether the project design could be optimized to reduce construction costs.
The project would provide a major benefit to farmers who depend on irrigation water from the Weiser River system, which doesn’t have a lot of storage capacity, said Weiser Irrigation District Chairman Vernon Lolley.
“It would guarantee us a full supply of water every year,” he said. “It would make our life so much easier.”
He said it could also benefit other irrigators in southern Idaho because some of the 400,000 acre-feet of water the state is required to send downstream each year to the Columbia River system to augment flows for endangered fish could be delivered from the Galloway dam.
The upper Snake, Payette and Boise river system are required to release 200,000, 160,000 and 40,000 acre-feet of water, respectively, each year for that purpose.
Delivering much of the state’s required fish flow water from the Galloway site could free up a lot of water for irrigation in those basins, project supporters say.
WID Secretary Jay Edwards said the reservoir could open the possibility of a couple thousand additional acres of cropland in the Weiser area.
“It would be humongous for the whole Weiser River drainage,” he said of the reservoir. “It would make the situation much better for everybody.”