Future water supplies will be stressed with little to no snow in Western mountains

The U.S. will need to make some serious changes to its water supply strategies as Earth’s climate continues to warm and snowpack in the country's Western mountains becomes much harder to come by in the coming decades, according to a new study.

In America’s long and often strained history of managing its water infrastructure massive amounts of water from mountain snowpack has long been viewed as a comforting constant. Frigid temperatures and frequent snowfalls allow nearly 162 million acre-feet worth of snow to accumulate in the Western mountains each year, only to melt during the spring and summer seasons when it becomes a key component of America’s water supply.

But, as with countless other things, climate change is about dramatically change that.

In a study published in the science journal Nature, experts warn that human-driven climate change is currently on track to send the country's supply of snow plummeting. Scientific circles largely agree that if current trends keep up, roughly a quarter of the snowpack in the Western mountains will be gone by 2050.

Data models suggest there is even a future where snowpack could disappear entirely in these areas on a persistent basis — and it may happen much sooner than we think.

“There is less consensus on the time horizon of snow disappearance, but model projections combined with a new low-to-no snow definition suggest ~35–60 years before low-to-no snow becomes persistent if greenhouse gas emissions continue unabated,” the study states.

Scientists stress that these changes could prove catastrophic for communities that rely on the water from snowpack. According to the study, assuming that the Western mountains of the U.S. lost around 54 million acre-feet of snow storage that was valued at around $200 per acre-foot with little-to-no snow conditions cropping up within the next century, economic costs reach up to $850 billion dollars — more money than the U.S. is shells out annually on defense spending.

“Moreover, the disappearance of snow in the [Western United States] has important hydrologic ramifications on both natural and managed systems,” according to the study. “Changes in the seasonal snow cycle influences the timing and magnitude of groundwater recharge, vegetation dynamics and stream discharge, which then directly impacts water availability.”

Experts say the Western U.S. will likely need to make some serious changes to its water infrastructure. Future water management strategies could include entirely new surface storage capacity projects, not unlike the proposed Sites Reservoir project in California, and while they can prove costly and take time to develop, other strategic dams and canals might be called for.

Current infrastructure can also be retrofitted with modern innovations to be more effective. One option would be to use forecast-informed reservoir operation that allows reservoirs to retain or release water more strategically based on advanced weather and hydrologic forecasts. A recent case modeling study on Lake Mendocino showed that an approach such as this could increase water storage by 33%.

“A path forward can be made by including Earth scientists, infrastructure experts, decision scientists, water management practitioners and community stakeholders, in a collaborative, iterative process of scientific knowledge creation through a co-production framework,” the study states.