The snowpack in the Sierra Nevada mountains has reached its lowest level in 500 years.

A new study from the University of Arizona examined tree ring data from 1405-2005 and snowpack measures since the 1930s.  The results showed what the research team called “unprecedented” loss.

“Our study really points to the extreme character of the 2014-15 winter,” Valerie Trouet, an associate professor of dendrochronology at the UA Laboratory of Tree-Ring Research, said in a press release. “… We should be prepared for this type of snow drought to occur much more frequently because of rising temperatures.”

Trouet added that 2015 was a record year because of the double blow from the extreme drought and record heat.

“What happened in 2015 is that very low precipitation co-occurred with record high temperatures. And that’s what made this snowpack low so extremely low,” Trouet said.  “We didn’t expect it to be this bad.”

The snowpack is vital for water supplies throughout California.  The California Water Project’s information officer told National Geographic they can only provide 20 percent of the water requested by customers.

There also appears to be no relief on the horizon.  Climatologists say that 2015 could be the hottest on record and that 2016 will be even warmer.