JEROME– The Eastern Snake Plain Aquifer (ESPA) experienced the single largest increase in water volume in more than 80 years – 1.7 million acre-feet – as a result of the Idaho Water Resource Board’s managed aquifer recharge program, farmers reducing water use, private aquifer-recharge efforts, increased tributary flows, and natural seepage from two back-to-back robust winter runoff years.
Mike McVay, a professional engineer and hydrogeologist for the Idaho Department of Water Resources, said the ESPA volume increase was calculated from the measurement of more than 350 wells across the ESPA region. It reflects the board's steadily expanding aquifer-recharge program, which sent 545,000 acre-feet of water into the ESPA in the winter of 2017-18, and more than 317,000 acre-feet of water into the ESPA in the winter of 2016-17. The board’s goal is to recharge an average of 250,000 acre-feet per year.
The increase also reflects a historic 2015 water settlement forged by farmers in the ESPA region who irrigate with surface water and groundwater, and two winters in a row with “exceptional precipitation,” officials said.
“We’ve had a significant uptick,” McVay said. “But we have to remember that this is a long-term proposition, and this is a good start. We need to build the aquifer back to sustainable levels over time.”
Before the winter of 2017, the Water Resource Board estimated that the aquifer was being over-drafted by about 200,000 acre-feet per year. Water from the ESPA drives the economy in eastern Idaho and south-central Idaho’s Magic Valley, serving agriculture, industry, manufacturing plants, municipal uses and drinking water for more than 400,000 residents.
Farmers participating in the 2015 water settlement should be commended for their part in stopping the aquifer decline, said Mat Weaver, deputy director of IDWR. “The reductions and private recharge that have occurred as a result of the settlement agreement have been hugely impactful,” he said.
“I’m pleased to see these results – I know that wet years help a lot, but we’re obviously getting a good return on our investment from the recharge program,” said Representative Lance Clow of Twin Falls. “I’m hoping that we can continue to do large amounts of recharge this coming winter. I think we need to keep expanding our infrastructure for recharge.”
Dean Stevenson, chairman of the Magic Valley Ground Water District, a participant in the 2015 water settlement agreement, said it was good to see positive results on ESPA water levels. “We have to remember that really we’re just getting started with the recharge program and the water settlement implementation. The long-term trend is what matters. We have to stay the course,” Stevenson said.