□ □ □ □
□ □ □ □ □
□? □ □ □
Reservoir levels also remained below average in many areas of the West , and at the end of the month 61 % of the western United States was in moderate to extreme drought , based on a widely used measure of drought , the Palmer Drought Index . At the end of September , 64 percent of the western U. S. was in moderate-to-extreme drought , compared with 68 percent for August and 79 percent for last year at this time , based on a widely used measure of drought , the Palmer Drought Index . At the end of the summer , 69 percent of the western United States was in moderate-to-extreme drought , compared with 76 percent at this time last year , based on a widely used measure of drought , the Palmer Drought Index . For example , the Palmer Drought Severity Index has been widely used by the U.S. Department of Agriculture to determine when to grant emergency drought assistance , but the Palmer is better when working with large areas of uniform topography . Reservoir levels also remained below average in many areas , and at the end of the spring 67 % of the western United States was in moderate to extreme drought , based on a widely used measure of drought , the Palmer Drought Index . The percentage of the West in moderate to extreme drought ( based on a widely used measure of drought , the Palmer Drought Index ) increased from 7 % in December , to 18 % in January .