May 12, 2015 – CALIFORNIA, UNITED STATES – If California’s prolonged dry spell is eventually recognised as a megadrought, no one can say we weren’t warned.
Lake Mead, the largest reservoir in the US, has hit its lowest level ever.
Feeding California, Nevada and Arizona, it can hold a mind-boggling 35 cubic kilometres of water. But it has been many years since it was at capacity, and the situation is only getting worse.
“We’re only at 38 per cent full. Lake Mead hasn’t been this low since we were filling it in the 1930s,” said a spokeswoman for the US Bureau of Reclamation in Las Vegas.
If it gets much lower – and with summer approaching and a dwindling snowpack available to replenish it, that looks likely – official rationing will begin for Arizona and Nevada. The hydroelectric output of the Hoover dam (below), to which the lake owes its existence, could also suffer.
Water restrictions are already in place in California, but some hydrologists say rationing there must start soon to avert disaster.
A drought must last at least two decades to be considered a megadrought. California’s dry spell isn’t quite there yet – it has endured for 15 years – but has already been classed as the worst drought of the last 1200 years.