Preparation of Average Annual Runoff Map of the United States, 1951-80

Average annual runoff was computed or estimated for 2,148 hydrologic cataloging units in the United States and Puerto Rico, for the period 1951-80. Runoff was computed from the recorded streamflow at 5,951 U.S. Geological Survey gaging stations. The runoff at more than 3,000 of these stations was estimated by correlation with other nearby stations to adjust for missing data. These runoff data were used to draw a map depicting the variation of runoff throughout the nation. Average annual runoff varied from less than 0.01 inch in parts of the Great Basin (Utah, parts of Nevada, Oregon, and California) to more than 240 inches in southeastern Alaska. (USGS)