Posted: Friday, March 15, 2013 10:33 AM
By JOHN O'CONNELL
POCATELLO, Idaho -- If a warming trend continues, Idaho State University biologist Colden Baxter predicts peak flows will occur progressively earlier in the Salmon River, eventually happening in winter rather than spring in some years.
ISU geosciences researcher Nancy Glenn has studied how climate change has shifted vegetation in the Upper Snake River area, contributing to bad fires and dust storms that deplete grazing allotments of soil nutrients.
Scientists from ISU, Boise State University and University of Idaho have begun publicizing findings as they wind up a five-year, $15 million federal grant through the National Science Foundation to cooperatively study Idaho's changing climate and water resources. ISU's share was $4.4 million, also used to hire new faculty to "fill gaps in expertise."
Grant projects focused on the Salmon, a system with largely unmanaged flows, and the Upper Snake, which fills a network of storage reservoirs.
Baxter said early flows could reduce water supplies for pastures irrigated by the Salmon River. Based on past data sets, information he's gathered and mathematical modeling, he estimates 3 degrees of warming -- anticipated by 2080 -- would hasten peak flows in the Middle Fork Salmon River tributary Big Creek by 23 to 50 days.
"It takes that long for things to show up on average, but we're seeing a lot of variability now in the timing of water delivery," Baxter said.
Civil engineering professor Venkat Sridhar' calculates snow water equivalent below 7,000 feet in the Upper Snake will decrease 35-75 percent by 2040-2070, and peak snow accumulation at that elevation will occur a month earlier than the current March 22 average by 2040-2050.
"We see the same signatures in stream flow," Sridhar said.
Glenn, head of the grant, and her colleagues have set up climate monitoring stations throughout the plain. She's found increasing moisture losses in vegetation, coupled with a rise in nonnative species, have already affected the local fire cycle.
"We have found fires are more frequent and more devastating. They tend to burn more vegetation, which causes increased erosion," she said. "We've also found wind erosion is more prevalent than we originally thought."
Lynn Tominaga, executive director of Idaho Groundwater Appropriators, believes the university research illustrates the need to plan for more water storage. He said the region has seen more extreme highs and lows in terms with moisture during the past two decades, and new storage reservoirs could help in wet years.
Tominaga would also like to see a massive canal system built leading far into the desert to facilitate aquifer recharge.
Paul Edwards, who manages a cattle ranch that irrigates from the Salmon River, has noticed no changes in water flows and doubts the validity of the longterm predictions.
"I don't think the Salmon River is going to change. It's been good, and it won't fail," Edwards said.
Edwards believes better management could help to immediately improve the fire outlook, having been concerned about firefighters waiting too long to start battling wildfires. He'd also like to see more logging conducted to thin forests.