Last November, to illustrate the severity of the drought, we published these photos of Lake Oroville over a 20-month period. (The lake was "sort of a drought poster child," wrote Lisa Pickoff-White.)
In that same vein, here are three satellite images from NASA of the Lake Tahoe region, from February 2011 to February 2014, showing the diminishing amount of snow. The images come from the agency's site Images of Change.
Things have only worsened since then. Check out this gif of the Sierra snowpack comparing satellite images from April 2014 with March 2015.
Now, courtesy of NASA again, here's Yosemite's shrinking Lyell Glacier: