Wind River Basin facing ‘tough’ irrigation season as river flows decline

(Fremont County, WY) – Local water experts say this summer may be a “tough” one for irrigators who are facing dry conditions and low streamflows across the Wind River Basin.

Early spring

A lack of low-level snowfall during the late winter and early spring, combined with warm March temperatures, caused snow water equivalents in many locations to peak and start melting three to five weeks earlier than normal this year, Wyoming Water Division III Water Superintendent Josh Frederickson explained this week.

After that initial “spring surge,” Steve Doyle with the Riverton Valley Irrigation District said river levels fell “much lower than you would expect” by early May.

“The temperatures have been so cool,” Midvale Irrigation District Manager Steve Lynn explained at that time. “It’s going to take a while for temperatures to warm up and get that high elevation snow down.”

The situation led to a delay in water delivery for Midvale irrigators, who were initially slated to start receiving water on April 27 but ended up having to wait until May 11, when Lynn said temperatures had warmed enough to increase local streamflows.

The irrigators were restricted to using 1 cfs of water per 70 acres at that time, though, he noted in June, and “when the river dies off and we go straight to storage” out of Bull Lake, “the commissioners will come up with an allotment, and we’re going to go to 1 cfs per 100 acres.”

The ‘big question’

The “big question” this year, Lynn said, is “how long will the river last” and “how much (water) we’ll get into Bull Lake” before then.

“We’ll be really blessed if we get another couple three weeks of river flow before we have to go to storage,” he said. “I’d love for it to run to the middle of July.”

For comparison, Lynn said that during a “good water year” Midvale irrigators are able to utilize river flows through July and into August.

Those streamflows are declining now, Frederickson said this week, pointing out that the SWE for the Wind River Basin currently sits at zero.

“That does not mean that every bit of snow in the mountains has melted – just at the sites where the SWE data is collected,” Frederickson said. “(But) generally the earlier the SNOTEL sites melt out, the earlier streamflows peak.”

Soil moisture

This year, streamflows in the Wind River Basin peaked in late May, Frederickson said – one to three weeks earlier than normal – so even though there have been sufficient flows in the Big Wind and Popo Agie rivers to satisfy irrigation demands so far, “as streamflows continue to recede, water supplies for irrigation will get tighter, and the likelihood of regulation requests, particularly for the Middle and Little Popo Agie Rivers, will increase.”

Part of the problem, he noted, is that soil moisture levels in the basin are low, so despite precipitation values being “decent” locally, most of that water “has soaked into the ground and not caused streams to rise significantly.”

Tribal Water Engineer Lokilo St. Clair has seen the impacts of that low soil-moisture content on his irrigation system, which has struggled to deliver water “to the very ends of some of our longer laterals.”

“The soil has taken longer to saturate,” he explained. “We’re having a hard time trying to get those groundwater levels back up to where you can push the water instead of sucking it all up. … We are making the necessary adjustments to try to get that water pushed to the very end of those laterals.”

Drought

According to the U.S. Drought Monitor (USDM), which uses soil moisture as a variable, drought conditions have worsened in Fremont County since March, when most of the local area was classified as D0 (Abnormally Dry) and D1 (Moderate Drought), Frederickson said.

Now, he said, most of Fremont County is classified as D2 Intensity (Severe Drought) – but on the Wind River Reservation, St. Clair said the Wind River Water Resources Control Board set the rating at D4, or Exceptional Drought, based on the USDM ranking system.

That rating was issued in January, St. Clair noted, “because of just the harsh, dry winter we’ve had.”

“It was a year that I kind of dreaded,” St. Clair said. “With not getting any snow in October or November or December, I figured that we were going to have a bad year. But also … we kind of noticed that a lot of these high-elevation snows haven’t been recharging. We’ve seen certain areas (where) the snowpack just isn’t there to sustain a good flow through the whole year.”

Based on current conditions, St. Clair predicted that his team would be able to provide water to their irrigators through the end of July – but in August, “we’re probably going to have to shut down.”

“We need the precipitation here,” he said. “Hope and pray that we get something (in) July and August, because we’re going to need it to help.”