A historic drought is spreading across California and much of the American West. How bad is it? Which places are most affected? What does it mean for our water supply and wildfire risk?

These 10 maps and charts tell the story.

Over the past two years, rain and snow totals in Northern California, Nevada, Utah and other parts of the West have been less than 50% of average. As this map from the Western Regional Climate Center in Reno shows, the drought is severe and widespread.