Measurement of 1999 drought conditions in Mississippi

Accurate and reliable water-resources data collected during drought conditions are critical to regulatory agencies such as the Mississippi Department of Environmental Quality (MDEQ). Droughts have affected Mississippi during 1940-44, 1951-57, 1962-71, 1980-82 and 1983-88. In late summer and early autumn 1999, many areas of Mississippi experienced near record drought conditions causing concern to many private and public interests. Personnel from the U.S. Geological Survey (USGS), in cooperation with the MDEQ Office of Land and Water Resources (MDEQ-OLWR) measured water levels and streamflows throughout the State of Mississippi during drought conditions in August through October 1999. Droughts are normal, recurring hydrological events caused by deficiency of precipitation over an extended period of time that can have adverse effects on anthropogenic use of water. Much of the State of Mississippi has continued to experience drought conditions through late winter of 2000. Data on minimum streamflows are an important factor for determining the regulation of flow control structures, effluent discharge, and surface water withdrawals and other water-management decisions during droughts. Data on minimum streamflows become paramount during drought conditions. This report presents information related to the legal aspects of drought conditions and includes selected data collected at streamgages affected by severe drought conditions in Mississippi during the late summer and early autumn of 1999. Comparisons of low-flow characteristics at selected streamgages to other period-of-record low-flows at selected gages in the State are also presented.