Statistical summaries of ground-water level data collected in the Suwannee River Water Management District, 1948 to 1994

Since 1948, ground-water level data have beensystematically collected from selected wells in theSuwannee River Water Management District (SRWMD) by the U.S. Geological Survey (USGS),the SRWMD, and other agencies. Records of waterlevels in the SRWMD (fig. 1), collected by the USGS and SRWMD through 1990, and by the SRWMD from 1990 to 1994, have been published for many years in the USGS annual report series "Water Resources Data for Florida." However, no systematic statistical summaries of water levels in the SRWMD have been previously published. The need for such statistical summary data forevaluations of drought severity, ground-water supplyavailability, and minimum water levels for regulatory purposes increases daily as demands for ground-water usage increase. Also, much of the base flow of the Suwannee River is dependent upon ground water. As the population and demand for ground water for drinking water and irrigation purposes increase, the ability to quickly and easily predict trends in ground-water availability will become paramount. In response to this need, the USGS, in cooperation with the SRWMD, compiled this report. Ground-water sta tistics for 136 sites are presented as well as figures showing water levels that were measured in wells from 1948 through September 1994. In 1994, the SRWMD and the USGS began a long- term program of cooperative studies designed tobetter understand minimum and maximum streamflows and ground-water levels in the SRWMD. Minimum and maximum flows and levels are needed by the district to manage the surface- and ground-water resources of the SRWMD and to maintain or improve the various ecosystems. Data evaluation was a necessary first step in the long- term SRWMD ground-water investigations program, because basic statistics for ground-water levels are not included in the USGS annual data reports such as "Water Resources Data for Florida, Water Year 1994" (Fran klin and others, 1995). Statistics included in this report were generated using the USGS computer pro gram ADAPS (Automatic Data Processing System) to characterize normal ground-water levels and depar tures from normal. The report has been organized so that the statisti cal analyses of water levels in the wells are presentedfollowing this introductory material, a description ofthe hydrogeology in the study area, and a description of the statistics used to present the water-level data. Specifically, the report presents statistical analyses for each well, as appropriate, in the following manner: Description of the well.Hydrographs of ground-water levels for the period of record, for the last 10 years of record, and for the last 5 years of record. Graphs of maximum, minimum, and mean of monthly mean ground-water levels for wells with 5 or more years of record.Frequency hydrographs (25, 50, and 75 percent) of monthly mean ground-water levels for wells with 5 or more years of record. Water-level data and statistical plots are grouped by county and sorted within the county by ascendingsite identification number. Well locations are plottedon county maps preceding the well descriptions andhydrographs.