The persistent drought plaguing California has devastated many of the state's trees.
An estimated 12.5 million have died, largely due to the stress the lack of water has put on the forest system.
Last month, the U.S. Forest Service conducted two aerial surveys covering around 8.3 million acres.
In southern California, the survey revealed approximately 2 million trees have died across private lands and national forests including San Bernardino and Angeles.
And in an assessment of the Sierra Nevada area that encompasses Yosemite and Sequoia-Kings Canyon National Parks, they found nearly 10.5 million dead trees.
In addition to a lack of water, trees are also dying off because of infestations of bark beetles that eat away at them.
Under hydrated and healthy conditions, the trees naturally produce a resin that keeps the insects away.
Dead trees mean a high risk of fire and lower water quality due to their inability to keep particulates from entering waterways.
Millions of additional trees are expected to die as summer arrives and the drought continues.