Irrigation company finds better way to manage supply
By Carol Ryan Dumas
SHOSHONE, Idaho — Faced with a short water supply for the 2013 irrigation season, the Aberdeen-Springfield Canal Co. in southeast Idaho relied on innovation and cooperation from its 400 customers to save water.
In previous short years, the company cut off water deliveries mid season for a period of time to save water for harvest. In 2004, deliveries were shut off for 22 days and the company still didn’t get a full season of water, said Steve Howser, the canal company’s general manager.
“It wasn’t very efficient and didn’t do a good job,” he said during a water efficiency and drought workshop, hosted by the University of Idaho and Idaho Power in Shoshone Feb. 24.
The company owns storage water in Jackson Lake, and in Palisades and American Falls reservoirs. Due to an insufficient snowpack in 2012 and 2013, its Palisades water supply was deficit 45 percent, and its final 2013 allocation for storage water was only about half of normal, he said.
The company’s models indicated it would run out of water by mid-August, and it needed to take drastic, new measures to extend its supply as far as possible, he said.
The old method of shutting water off had only resulted in digging a deeper hole. Alfalfa growers couldn’t get their third cutting and potato and sugar beet growers took a loss in yield, So managers came up with a different plan, he said.
For 100 years, water was managed to meet the demand of shareholders. Instead, the company decided to manage the supply from the top down, limiting how much water was available on a daily basis, he said.
It wasn’t an easy change, but it was accomplished with the full cooperation of shareholders, he said.
Avoiding shutting off deliveries and keeping water in the system saved water because the company’s earthen canals, which operate beside desert land, are very leaky. When the water is turned off, the water that has leaked into the ground beneath the canal drains away and when it’s turned back on, that void is refilled with additional canal water, he said.
The longer the water is turned off, the more days it takes to fill that void. The strategy was to avoid turning water off to stretch the water supply, he said.
The company also changed its deliveries to prevent spills at the bottom end of the system and called for a 72-hour prior notice of water needs so managers could more tightly control diversions.
It also rotated deliveries for a maximum delivery of six days in a row followed by two days off. That allowed for a daily cap on each reach of the system of 62.5 percent of average.
There was enough acreage every day not taking water to keep the reach under the daily cap and provide producers their normal delivery, he said.
The canal company also had ditch riders making changes to head gates twice a day instead of once to save water that might otherwise go unused for 10 to 12 hours. The company also added additional monitoring and control stations and bought flow meters to test pumps and tailor deliveries to those needs, he said.
The company urged shareholders to maintain sprinkler systems to maximize efficiencies, defer watering stubble until later in the season if possible and to only order the amount of water they needed.
The measures minimized through-the-head gate spills and helped flatten out daily spills at the bottom of the system. The canal company reduced spills back into the river by 52 percent and was able to deliver 68 percent of the normal storage water supply, he said.
Alfalfa growers were able to get a third cutting, and while potato and sugar beet yields were down a bit – 5 percent or less – it was nowhere near the 20 to 30 percent losses they experienced in the 2001-2004 drought years and could have been attributed to an extremely dry spring and hot, dry summer, he said.
Every system is different, and what worked for Aberdeen-Springfield might not work in other systems. But it does show “you don’t have to do things the way they’ve been done for 100 years,” Howser said.
“There’s always something else you can do to get through the drought,” he said.
But it takes a lot of cooperation from water users, ditch riders and managers, he said.