Drought occurs when the expected availability of water is more than the actual availability. Desert or arid regions where precipitation and available water resources are relatively scarce are particularly susceptible to drought. Such is currently the case in the American Southwest.
Normal precipitation for the region--including the southern Plains, the Southwest, and northern Mexico--is only about 6 inches for the October through May period. In 1995 and 1996, however it was much lower; less than 1 inch was observed in some places. The resulting dryness has severely impacted unirrigated crops and pasture land. Supplies for irrigated agriculture, domestic use, and other use are generally sufficient but are being stressed by demands. By June 11 this year, wildfires had charred 1.5 million acres south and west of the Ohio River as compared to 390 thousand acres for the same period last year.
Drought may be defined in a number of ways: There is meteorological drought where precipitation is below expected amounts. There is agricultural drought when crops or livestock are impacted by water shortages. Another way to define drought is through hydrology. When supplies--streamflow, water in reservoirs, and water available to wells--are insufficient to meet demands, hydrologic drought occurs.
This site primarily deals with hydrologic drought. Although impacts to agriculture, water-use statistics, effects on wildlife and recreation, and meteorological data will be presented as available to illustrate the drought, emphasis will be on the availability of water resources.
The U.S. Geological Survey nationally operates over 7,000 stream gages that continuously monitor the flow and level of streams. At thousands of other sites, the Survey monitors ground-water and reservoir levels or measures water-quality. Some of these data are available through links with this site; other data are available by contacting the appropriate Survey district (state) office. Telephone numbers, e-mail addresses, and postal addresses are available through the links.
This page, in addition to the links, shows national streamflow conditions for the past month and for the same month during historic drought that have impacted the Southwest. The month will be updated as data for the subsequent month become available.