Each summer a massive $5.25 million irrigation system is cranked on at the National Elk Refuge, showering beads of water over nearly a fifth of the preserve’s 25,000 grassy acres.
With no crops growing and no livestock in sight, tourists and newcomers to Jackson Hole who catch a glimpse must occasionally be bewildered.
But there are actually many reasons for the refuge’s irrigation system, new as of 2010.
The primary goal is to give the refuge’s 7,000-some wintering elk more and better quality eats, thereby reducing dependence on alfalfa distributed at feed lines. And the sprinklers are working, said refuge biologist Eric Cole.
“We’ve increased forage production and the quality of the forage significantly using the new irrigation,” Cole said.
The proof is in the numbers: This summer an estimated 2.4 million pounds — about 1,200 tons — more grass and other plant matter sprouted up because a team of seasonal employees maneuvered around 48 miles of pipe, ultimately watering about 5 square miles of refuge property.
Cole figures the elk refuge would have supported 9,685 tons of herbaceous forage had there been no irrigation system. Instead, 10,885 tons of elk food grew, meaning there was a 12 percent bump in production.
The elk refuge’s sprinklers, known as a “K-line” system, was made possible in large part because of a $4.3 million grant from the American Recovery and Reinvestment Act.
The sprinkler’s size may be unprecedented in scope, Cole said.
“To my knowledge, this is the largest K-line irrigation system in the world,” he said.
Another hope is that the irrigation system will cause the refuge’s wintering elk population to spread out. Maladies like chronic wasting disease, always-fatal but so-far absent on the refuge, and foot rot are transferred more easily among closely quartered elk. It remains to be seen if the sprinklers are dispersing them, Cole said.
“The jury is still out on that,” Cole said.
Data has been collected but a report is still in the making.
“Anecdotally,” Cole said, “I think we’ve seen increased use of the Poverty Flats area.”
A second, perhaps more surprising goal of the sprinkler system is that it’s also supposed to help hunters get their elk.
“We’ve used [the irrigation system] in the past as a management tool to try to lure animals into open hunt areas to meet our objectives,” Cole said. “We’re above objective, at least according to our management plan.”
In one sense the elk refuge’s sprinkler system is a reminder that Mother Nature still rules the day.
In 2013, despite the 12 percent increase in grasses and other feed from irrigation, refuge-wide forage was down nearly a quarter from the 15-year average. The reason: a lack of natural precipitation. And when the rain did fall, it came too late.
“Although precipitation in September was well above average, these rains occurred too late in the growing season to have a major effect on forage quantity,” Cole wrote in a recent report summary.
“Although irrigation significantly bolstered forage production, it did not completely mitigate for drought effects,” he wrote.