Idaho to Start Winter Recharge
by John O'Connell
The Idaho Department of Water Resources and three irrigation water providers
plan to conduct the state's first extenive winter aquifer recharge effort soon.
BURLEY, Idaho -- Three Milner Reservoir storage purveyors have agreed to help the Idaho Department of Water Resources start conducting winter recharge this season within the Eastern Snake Plain Aquifer.
American Falls Reservoir District No. 2, Southwest Irrigation District and Twin Falls Canal Co. were enticed to join the pilot project by a new tiered payment program that awards greater payments per acre foot for longer durations of recharge. The program, approved in August, utilizes a state-held recharge right, which remains in priority throughout winter for a base flow of 500 cubic feet per second below Milner, where Idaho irrigators can't otherwise put the water to beneficial use.
IDWR hopes to recharge up to 100 cubic feet per second through seepage from 31 miles of AFRD No. 2's unlined canal and an additional 150 cubic feet per second by diverting water to the district's Milepost 31 recharge basin. IDWR aims to recharge 50 cubic feet per second through the Twin Falls Canal down to Murtaugh Lake. Southwest plans to recharge 25 cubic feet per second this winter through a series of injection wells. Models show a large percentage of the recharge from all three systems will remain in the aquifer beyond five years.
Previously, IDWR paid a flat rate of $3 per acre foot in "wheeling fees" to defray irrigation companies' recharge costs. The tiered structure ranges from $3 per acre foot for up to 25 days of recharge to $14 per acre foot for more than 120 days of recharge.
IDWR Deputy Director Mat Weaver said the state has an annual goal of recharging at least 100,000 acre feet. The goal is scheduled to increase to 250,000 acre feet in a couple of years, but IDWR has averaged only 75,000 acre feet per year since 2009. The tiered structure should make recharge more cost-effective during winter, when there's no competition with canal maintenance but weather is a hassle.
AFRD No. 2 intends to install a bubbling system to prevent freezing of certain canal gates.
"(The tiered structure) definitely came a long ways to make it a lot more feasible to cover your costs," said Lynn Harmon, manager of AFRD No. 2.
IDWR is also working to get Northside Canal Co. to participate but must address concerns about water freezing in hydropower turbines located on the company's main canal. Harmon hopes to eventually recharge every other year, taking turns with Northside, and conducting more in-depth system maintenance in off years.
In the future, AFRD No. 2 could winter recharge an additional 250 cubic feet per second at a basin near Shoshone, provided that improvements are made to fortify a stretch of old, concrete canal. Furthermore, IDWR is researching potential sites for building injection wells where it could conduct its own recharge.
IDWR has access to one-time state funding to cover wheeling fees this season and will have access to state cigarette tax dollars for aquifer recharge beginning next year.
Idaho Groundwater Appropriators Executive Director Lynn Tominaga said his organization intends to introduce legislation in the coming session creating a system for selling credits tied to the state recharge program that could be used to mitigate for future delivery calls. Similar proposals failed to pass the Legislature last session because the parties involved failed to reach a consensus.
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