The scenic and pastoral Big Lost River has always lost water, eventually vanishing in the sagebrush deserts of the Snake River Plain. But in recent years, more and more water has vanished in a reach near the town of Darlington that's aptly called the Darlington Sinks.
A variety of Big Lost stakeholders are teaming up this summer to find out why and to maybe put a stop to the phenomenon. This week, the stakeholders announced a federal agency has doled out $107,000 to help evaluate the feasibility of improving river flows below Darlington.
The Big Lost is fed by tributaries on the east slopes of the Boulder, Pioneer and White Knob mountains and the west slope of the Lost River Range. It meanders through cottonwood groves and through or near the rural cities of Mackay, Darlington and Moore, before disappearing in the porous soils of the Snake River Plain in a sink northeast of Arco.
Prior to this year, the riverbed near Arco had long been dry, the entire river diverted for agricultural use upstream.
The grant, provided by the U.S. Department of Agriculture's Natural Resources Conservation Service, will facilitate the study of water loss at Darlington Sinks. It will also help develop alternatives for reducing water loss there, potentially benefiting irrigators, conservation groups and the community at large.
What those projects might look like, however, will be up to the scientist who is hired.
"I don't know (what the projects will look like). I'm not a geomorphologist," said Kim Goodman, the director of Trout Unlimited's Idaho Water Office. "I'm really looking for a professional to tell us what our options might be."
A scientist should be on board by this fall, she said.
In the past, the Big Lost has been eroded and channeled. That has increased sedimentation in the Darlington Sinks, and that may be contributing to the water loss, Goodman said. The theory is that, as the river spreads out in various channels, it also seeps into the ground at accelerated rates.
Trout Unlimited, Idaho Water District 34 and the Big Lost River Irrigation District requested the funding in March.
"This is a very important grant in that it will help to provide the means whereby a diverse group of interests will take the initial steps to restore streams flows to the benefit of all," Goodman said.
According to Trout Unlimited, the loss impacts both agricultural producers and fish. During low flows, water typically doesn't make it to downstream water users, even those with senior water rights.
What's more, habitat for fish species dries up. The Big Lost is home to historically healthy populations of rainbow trout, as well as Big Lost mountain whitefish, a species that a Hailey-based environmental group, Western Watersheds Project, petitioned for Endangered Species Act listing on June 14.