Today’s snow survey confirms abundant snow in the Sierra Nevada, an extreme turn from five years of drought. With climate change contributing to warmer winters in the Sierra Nevada, that snow may not stay put for long – an early snowmelt will cause flooding and require reservoirs to spill excess water that could threaten safety of California dams in the weeks to come.
As a consequence, Los Angeles’ Mayor Eric Garcetti recently declared a state of emergency for the small town of Owens Valley located in the foothills of the Sierra Nevada, nearly 300 miles from LA, where much of the city’s water supply originates. The mayor is worried that the melting mountain snowpack would flood the Owens Valley and overwhelm the LA Aqueduct, causing up to $500 million in damage.
Essentially, we have a timing problem. Our increasingly outdated water system relies on high elevation dams designed to fill slowly with snowmelt over the spring and summer, delivering water in the summer and fall when water demands are highest.
Today’s water system is experiencing earlier snowmelt that is filling reservoirs and forcing excess water to be spilled, leading to the type of flooding and infrastructure damage that we witnessed in Oroville and San Jose over the past two months.
This winter may be a sign of what’s to come.Dr. Alex Hall of UCLA presented new climate science research to policymakers in Sacramento this January, which concludes that the peak snowmelt, which has historically occurred in April, will shift to January by the end of this century. Our current system of dams, reservoirs and levees is not prepared to handle an extreme shift like that and will fail to deliver anywhere near the quantity of water it does today.
That’s why we must develop a more climate-resilient water system – one that makes more effective use of groundwater storage — a critical strategy to adapting to the loss of snowpack and the shift in the timing of water supply.
California’s underground aquifers have three times the storage capacity as all of the state’s above-ground reservoirs. With global warming increasingly causing precipitation to fall as rain rather than snow, it’s time to stop looking up to the mountains for our water supply and start paying attention to the larger storage capacity underneath our feet.