MILNER • Canals below Milner Dam started draining Wednesday — a little earlier than usual — as canal company workers ready the irrigation system for winter maintenance work.
The early closing of gates at Milner will save irrigation water for next spring, said Brian Olmstead, manager of the Twin Falls Canal Co.
Olmstead said Snake River water reserves above Milner are the lowest he has seen in almost a decade.
Most crops in the Magic Valley have been harvested or are near harvest, he said. But a few growers will use water until the last drop is delivered.
Alfalfa fields and grass pastures need as much moisture as they can get this time of year. Alfalfa and grass are perennials, so they use water all winter.
“Alfalfa uses a heck of a lot of water,” said Tony McCammon, University of Idaho extension educator in Twin Falls. Winter wheat will need additional moisture in the soil, also.
North Side Canal Co. closed its gates at Milner Dam last weekend, said manager Alan Hansten. North Side Canal delivers irrigation water to 160,000 acres in Jerome, Gooding and Elmore counties. The south side canal system irrigates 212,000 acres.
Both canal companies will be busy all winter preparing the canal systems for the next season. “Crews are now starting to assess what needs to be done,” Hansten said.
Workers will inspect riprap, replace concrete structures and remove sediment with excavators in canals that wind over hundreds of miles of southern Idaho farmland.
Riprap — a layer of boulders that lines the inside of canal walls — has protected canal banks against the ravages of moving water and ice since the systems were completed early in the 20th century.
Hansten said the big project planned for this winter is replacing the main canal’s diversion structure north of the Jerome Butte. The structure divides the main canal into three laterals.
The Twin Falls canal contains about 4,000 concrete structures, ranging from gates to a large diversion dam. The company replaces 100 of these structures each winter, Olmstead said.
The High Line Canal is nearly dry, and the Low Line will run a few more days as Murtaugh Lake empties.
In the meantime, the canal company is expanding the Kinyon pond south of Castleford, Olmstead said. The pond is a natural depression at the end of the High Line Canal at Deep Creek. When finished, the pond will cover 35 acres and will hold 200-plus acre/feet of water. The pond will be ready for next spring’s irrigation system.
Hansten said he has no idea when the canal systems will start again next spring. “It all depends on the weather.”
The two canal companies have storage rights in American Falls, and Jackson Lake reservoirs. North Side has additional storage rights in Palisades Reservoir.
But those reserves are extremely low. American Falls is only 7 percent full, Palisades is 9 percent full and Jackson Lake is 18 percent full.
“We’re all hoping for a good snow pack this winter.”