Water Board reviews aquifer recharge

A new report shows aquifer levels dropped slightly in the last year, but Eastern Snake Plain Aquifer (ESPA) spring flows are showing a general upward trend.

According to the Idaho Water Resource Board, the aquifer’s water volume is up 1.8 million acre-feet since 2015. Hydrologists told the board that could be credited to a string of wet winters, ESPA recharge flows, water reductions by ground water irrigators and other measures.

Department of Water Resources hydrologist Mike McVay reported the aquifer water level dropped by approximately 50,000 acre-feet, as measured at 377 ground water wells in late March and early April.

McVay said ESPA volume increased by 1.4 million acre-feet of water last year, the largest single-year increase in 80 years.

“I think we’re still doing a good job,” McVay said. “Most of the ground water well levels on the Eastern Snake Plain were holding steady or increasing slightly.”

The ESPA recharge program sent 362,400 acre-feet of water into the aquifer in the winter of 2018-19 while ground water pumpers reduced use by 240,000 acre-feet.

While the numbers bump up and down, hydrologists say the real key is maintaining an overall upward trend.

“We’ve got to stay on course and keep at this,” added Roger Chase, chairman of the Water Board. “We’re learning more about the aquifer every day, but we are on the right trend line.”

Brian Olmstead, general manager of the Twin Falls Canal Company, agreed that long-term trends are what matters. “After a year like 2017, you’re going to see a decrease, but the year by year data isn’t as important as the long-term trend.”

The Idaho Department of Water Resources is refining its measurement process to provide the most accurate picture possible.