The Big Wood River in Ketchum hit its lowest-ever recorded flows between June 8 and June 21 of this month, according to U.S. Geological Survey data. Previous low-flow records for that time period were set in 1966 and 2013.
From June 8-21, the Ketchum USGS gauge site recorded an average flow rate of 182 cubic feet per second—significantly lower than 583 cfs, the average flow rate for those two weeks. During the same time period this month, the Big Wood River in Hailey flowed at an average rate of 508 cfs, around one-third of the average flow (1,531 cfs) for those two weeks.
According to Natural Resources Conservation Service hydrologist Danny Tappa, below-average autumn precipitation, low winter snowfall and a dry spring have all contributed to a poor water supply outlook for this summer. The biggest concern will be for surface water users on Magic Reservoir and further south, he said.
Mark Davidson, director of conservation initiatives at The Nature Conservancy, said that cuts to irrigation water may occur as soon as the first week of July.
“We were anticipating this was going to be a really bad water year, and it seems to be playing out that way,” he said in an interview. “When you get into a drought cycle like this, water users and fish and wildlife can face real challenges.”
Davidson is hopeful that conservation organizations, groundwater-pumpers and surface-water users, such as ranchers, will engage in “solution-focused” conversations about sustainable water use this summer.
“There are many ways we can reduce water demand,” he said. “A few examples would be improving diversion structures to deliver water more efficiently to canals, improving irrigation delivery infrastructure by replacing ditches with pipes and reducing the percentage of irrigated land on a farm or ranch.”