In the past 50 years, the amount of snow that blankets the Douglas firs of the Cascade Mountains has fallen less thickly. There's been a hushed build up to the realization that this change is very real and, in the case of forest fires, could have a dangerous impact on Central Oregonians. But now, finally, scientists are beginning to sound the alarm bells with vigor.
"We should be concerned," said Kathie Dello, associate director of the Oregon Climate Change Research Institute at Oregon State University in Corvallis. "Across the Western U.S. [the snowpack] has overwhelmingly declined."
For the landscapes of the West, this means our natural water reservoirs, stored high in the mountains in the form of deep snowdrifts, are dwindling even as our populations are growing at an exponential rate—an equation that calculates to a rapidly increasing squeezes on water resources in the region.
Dello, whose organization has been studying the implications of declining snowpack for years, explains that if the trend of warming winters continues the impact will be most acutely felt in pinched salmon runs, lower hydropower generation, and the reduced recharging of aquifers; these problems are particularly pointed in arid regions such as the High Desert.
While research and data about regional snowpack dates to the 1930s—when researchers used remedial methods like jamming tubes into the snow to measure depths and density—more recent technology reveals even more precise data. These new tools include "snow pillows." Installed at over 150 locations in Oregon and Washington, these "pillows" sit near the ground and measure the pressure of the snow—sending electronic data about snowpacks to monitoring sites like the one near Bend—on a daily basis.
Melissa Webb, a snow hydrologist, helps manage snowpack data collection in Oregon for the National Water and Climate Center in Portland, which is part of the U.S. Department of Agriculture.
She says that while there's been a great degree of variability in the mountains near Bend, the overall, long-term trends definitively show snowpack declines.
The data she and other snow hydrologists collect in the Cascades is sent to the Climate Center for analysis. With it, the agency predicts streamflow, which is based on the melting of water in the snowpack—critical information for gauging impacts to seasonal tourism ventures and assessing water rights.
"If you are a user who irrigates and has junior water rights," said Webb, "you might get worried a lot sooner than someone with senior water rights."
In Central Oregon, as in much of the Western regions of the U.S., water rights are determined by seniority; first claimed, first served. Here, those senior water rights belong to irrigation districts that staked claims in the early 1900s when the state first began its water rights permitting program. As water supplies dwindle, the divide between junior and senior water rights will have increasingly pressing implications for the city of Bend's surface water program and for many of our efforts to get more water in stream and out of the canals crisscrossing the region.
But perhaps the most immediate concern is the sobering reality that less snow means hotter forest fires that arrive earlier in the season.
Webb's team now has soil moisture gauges in the ground all over Oregon and Washington. They pass that information on to the Forest Service each year to help that agency prepare for fire seasons.
Deeper snowpacks mean more water in the soil later in the spring, which helps dampen and push back the fire season, she said. Less snow means drier soil, drier vegetation and, if the trend continues, the precise tinderbox conditions for fires to rip through forests with blazing fury.
Because the trends are clear, climate scientists are less concerned with the current snapshot than using this data to prepare for a new, drier, water-scarce future.
"You start to ask a lot of complicated questions," concluded Dello, "but really what you are doing is trying to prepare yourself for what's going to happen rather than how to make it stop."
