Some six miles above Oregon’s Cascade Mountains, water vapor condenses around a speck of dust and forms ice crystals in the clouds. These start to fall, sticking together in the complex cluster of a snowflake that floats down to the mountain. With the ground temperature below freezing, the snowflake settles gently beside one of the state’s iconic Douglas firs, a delicate but vital contribution to the season’s snowpack. Countless snowflakes have fallen before it, and countless more will cover it, creating a vast store of frozen water that will melt with the arrival of warmer weather. For Oregon, the true value of the winter snowpack comes in the summer when its water is released precisely when it is needed most. But increasingly for Oregon, the billion-dollar question is will the snowpack bring enough water at the right time?

Snowpack, the snow that collects and stays frozen on mountains for months, is a natural water reservoir. Made up of multiple compacted layers from many different snowfalls, the depth of the snowpack is determined by the amount of snowfall and the influence of temperature (that melts surface layers) and wind (that can evaporate and erode the top layers). With the right conditions, snowpack can accumulate to depths of ten feet or more, releasing between 1 and 1.5 inches of water for every foot of snow. This snowmelt flows down the mountain, forming creeks, streams, and rivers that wind their way across Oregon, delivering a steady supply of water through the dry summer and into the fall. But Oregon’s snowpack is declining: less snowpack means less water and less water brings big problems.

Snowpack makes a major contribution to the state’s water: more than 70 percent of Oregon’s population live in the Willamette Valley where up to 80 percent of the summer stream flow comes from snowmelt. It is essential for replenishing the rivers, reservoirs, and aquifers that keep the environment healthy, crops growing, industry rolling, and faucets flowing. But Oregon has suffered successive years of drought, the longest lasting 270 consecutive weeks, until February 2017. The reprieve didn’t last long. By summer 2018, over 85 percent of the state was in severe drought as high temperatures delivered a low snowpack and reduced snowmelt that saw the state dry out quickly; the drought continued into 2019. As of this February, Oregon is free of severe drought conditions after a two-week dump of snow raised a dismal winter snowpack up to near normal—although normal isn’t what it used to be.

In the last ten years Oregon has only reached its historically normal snowpack four times, with the 2018-19 hydrological year not even reaching three-quarters normal. This year the historical values will be updated to include the last decade and the new normal will take into account the warm temperatures, early snowmelts, and prolonged dry stretches of recent years. Indeed, several years of low snowpack have made a new drought definition necessary—snow drought. This is a period of abnormally low snowpack caused by a lack of overall precipitation; a lack of snow accumulation, possibly because warmer temperatures bring rain instead of snow; or unusually early snowmelt. The timing is critical: In Oregon the snow has been coming later and the snowmelt starting earlier, which not only means less time for the snowpack to build, but also that what water there is arrives before it’s most needed, in the summer.

Climate change is certainly affecting snowpack, but a recent study suggests that natural weather variations may have shielded the Cascade Mountains from the full impacts of global warming. While snow stations have recorded a snowpack decline, the warming of the U.S. by more than 32 degrees Fahrenheit should have caused a more significant drop in snowpack, perhaps by as much as 54 percent over the last 35 years. If the weather changes and the shielding effect ends, the consequences could be serious for the snowpack: Oregon’s snow starts to form when it is close to freezing, so even a little warming could change snowfall into rainfall. Winter rain is better than no rain, but it can cause flooding and would need new infrastructure to be built to channel, capture, and store the excess water for the summer—something snowpack has done naturally for millennia.

The impact of reduced spring and summer snowmelt on Oregon could be devastating. With less streamflow and soil moisture, vegetation dries and dies, and that includes trees. Oregon’s forests are increasingly scattered with the skeletal remains of the state tree, the Douglas fir, weakened by water stress that leaves them vulnerable to pests and disease. Wildfire is another growing threat without the snowmelt to keep the ground moist. Low river levels make life difficult for fish such as spawning salmon that thrive on the surge of cold snowmelt; it also affects fishing and other activities on which tourism and local economies rely. A big economic loser is agriculture: without summer irrigation from snowpack water, crops wilt, pastures brown, and farmers have to buy in feed for livestock—Oregon’s 2015 drought caused hundreds of millions of dollars of damage in the sector. Snowmelt is also crucial for hydroelectric power, one of the state’s primary power sources. And finally, without snowmelt the municipal supply suffers, bringing seasonal water shortages to cities, towns, and households.

With the likelihood of less snowpack in the future, Oregon will have to adapt. Along with investment in new infrastructure ranging from reservoirs to desalination plants, everyone will need to use less water. Fortunately, there are big savings to be made. Simply turning off the faucet while brushing teeth or shaving can save two gallons per minute, and fitting a high-efficiency shower head can save over ten gallons a shower. Switching to a modern frontloading washing machine uses around 70 percent less water with an extra 10 percent saved for a full load. In the kitchen, simply not pre-rinsing your dishes before loading the dishwasher will save another 20 gallons. When done by the whole population, these small water saving actions can make a big difference; they can’t keep the snow forming and falling in the skies above Oregon, but they will help us make the most of what water we have.