Researchers collected runoff samples from river basins at 42 sites across the Mountain West, including Colorado, Idaho, New Mexico, Wyoming, and Utah. They used what's called tritium isotope analysis to determine the age of the water.
In other words, they were figuring out how much time had elapsed since the water flowing in the stream was snow falling in the mountains.
Researchers found that a snowflake that falls and melts will spend, on average, five years as groundwater before it seeps into mountain streams.
That means there's a whole lot more water stored underground than water managers account for, said Paul Brooks, a professor of geology and geophysics at the University of Utah and the study's lead author.
"By measuring the amount of water in storage in winter, we can provide early warning to water managers, reservoir managers, agricultural interests, who are making decisions about how they will allocate water for the upcoming season," said Brooks.
He added that this data will not only help improve future water supply predictions, it will also help emergency managers forecast and plan for floods and droughts, which are becoming more frequent and severe due to climate change.
"We know that conditions are changing," he said. "Whether it's fires or mortality of forests, climate change, and climate variability."
The study pointed out that federal and state water managers have largely relied on snowpack monitoring sites dotting western mountain ranges to guide forecasts and water availability for the upcoming year.
That snowpack data, however, doesn't provide a complete picture, according to researchers.
"For much of the West, especially the Interior West where this study was based, our models have been losing skill," Brooks said.
This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Nevada Public Radio, Boise State Public Radio in Idaho, KUNR in Nevada, KUNC in Colorado and KANW in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.
