What's Snow Got To Do With It? How Scarce Mountain Snowpack Affects Western Water

The bare peaks and dwindling snow on California's Sierra Nevada Mountains are terrible signs of the huge toll this ongoing, historic drought is taking on the state's water supplies. Snowcapped mountains aren't merely a beautiful backdrop, but also a high-elevation water storage system that the American West relies on for a substantial portion of its water supplies. In a normal year, California gets about 30 percent of its freshwater supply from snow melt runoff that feeds streams, fills the state reservoirs and provides water to everyone from coastal urbanites to farmers in the Central Valley.


"We're not only setting a new low, we're completely obliterating the old record," said David Rizzardo, head of snow surveys at the California Department of Water Resources.


Hard data confirmed the paltry Sierra snowpack when late-March sensor readings and the follow-up snow survey by the state water agency registered their lowest snow levels ever at 5 percent of average. "We're not only setting a new low, we're completely obliterating the old record," said David Rizzardo, head of snow surveys at the California Department of Water Resources. April 1st snow readings are important because they mark the high point of the snowpack and, in this case, show just how dire the situation is. The previous record-low, at 25 percent, was a tie between 2014 and 1977. Now, with little rain in the forecast, California essentially has all the water they're going to get for the year.

The severe conditions moved California Governor Jerry Brown to trundle across the Phillips Station (snow-free) snow course to announce an unprecedented executive order that mandated 25 percent reductions for urban water use from 2013 levels. Farmers felt the pain earlier in the year when agricultural water allotments were set at 20 percent and exactly zero of maximum expected deliveries from the State Water Project and the federal Central Valley Water Project, respectively.

"This historic drought demands unprecedented action," declared Governor Brown at the press conference. He added, "We're in a new era."

What does a "new era" mean for the snowpack of California and other runoff-dependent Western states? The "newness" comes in part from climate change and a likely shift in precipitation patterns for the vital Western mountain ranges that act as "islands of moisture in a vast sea of aridity." As temperatures in the West trend up over time - 2014 being California's warmest on record, for instance - Westerners will experience a shift in the hydrological cycle. (Don't forget that much of the state of Nevada is in exceptional drought and gets its water from Sierra Nevada runoff, too.) Warmer temperatures mean precipitation will fall as rain more than snow in high altitudes, disrupting the timing of snow to liquid water runoff to reservoirs, the mainstay of summertime water supply.

Interestingly, California might already be experiencing this, as it was big winter rainstorms - not snow - that filled the two biggest northern reservoirs and saved the state from an even worse state of water availability. This winter, the Northwest's Cascade Mountains have also experienced more rain and a lower snowpack, although reservoirs are stable. (See SNODAS-NOAA map in slideshow, above.) Faster rain-delivered runoff could also be harder to capture and translate into less groundwater recharge.

Along with the rise in temperatures, there will be a rise in evaporation which can lead to a greater probability of drought in some regions, as higher temperatures combine to increase the likelihood of longer and more intense droughts throughout the West. One recently published study pointed to the possibility of a long-term California "megadrought" by the end of the century, which the state has periodically experienced over the millennia.

This new era will affect the entire California water system and everything is up in the air: lower reservoir levels; lower stream flow; less hydropower; greater reliance on groundwater; changes in farming methods and crop varieties; and browner urban landscapes with less turf grass. While the water conditions for the rest of 2015 look grim right now, there is still hope because we have a grasp on the future. California and the rest of the West must adapt to a shifting water cycle and accept that water might not be there in the ways it has been in recent times. A new era means not only will water infrastructure have to change, but also peoples' mentality about water, its worth and how best to use it. Those images of snowcapped peaks should be valued as much for the vital role that snow plays in California and the West as for their grandeur.  

 

Image "looking back at matterhorn peak" by oliver.dodd on Flickr used under a Creative Commons Attribution 2.0 Generic license.