Water-level measurements for selected wells in the Jackson, Mississippi, area, October 1996-July 1997

Abstract

INTRODUCTION The U.S. Geological Survey (USGS) collects, on a systematic basis, data needed to determine and evaluate the ground-water resources of the City of Jackson, Mississippi. The USGS measures water levels in the Cockfield and Sparta aquifers underlying the Jackson, Mississippi, area to assess water-level trends. The purpose of this report is to present water levels measured in selected wells from October 1996 through July 1997 and associated historical water-level data. In addition, the subsurface sand and clay intervals at each well were determined and reported. METHODS Water-level measurements were made in two wells owned by the City of Jackson, Sparta wells M094 and Ml 12. In addition, water-level measurements were made in other wells in the Jackson area (fig. 1) to provide additional information on water-level trends. Measurements were made monthly from October 1996 through July 1997 using a graduated steel tape and battery operated water-level indicator. Hydrographs were constructed (figs. 2-12) using recent and historical water-level measurements. Measurements separated by a time period of greater than 2 years are shown as points on the hydrographs. In pumped wells, the water-level measurements were made after the well pump had been turned off and, generally, water levels were allowed a sufficient recovery time. However, short-term fluctuations in water levels can be seen on some hydrographs as dips, probably caused by insufficient recovery time of a pumped well, or caused by drawdown from nearby pumping wells. These dips do not represent the static water level and should generally not be used when evaluating the overall water-level trend. The subsurface sand and clay intervals at most wells were determined from geophysical logs (fig. 13). For this report, sand is used to indicate aquifer material (fine to coarse sand and gravel); clay is used to indicate confining material (clay and silt). It should be noted that logged intervals may be deeper or shallower than the interval in which the well was screened. RESULTS The results of the water-level measurements made at selected wells in the Cockfield and Sparta aquifers are shown as hydrographs on figures 2-12. Additional information for each well is listed in table 1. All of the hydrographs show an overall decline in water levels since the first measurements were made. The rates of water-level decline were calculated by using the hydrographs of several wells. Rates of water-level decline were determined from hydrographs using static water levels and were not simply the maximum difference in water levels over the period of record, which may not be representative due to nearby pumping wells. For two of the observation wells with the longest period of record, H023 and HI60, water-level declines at a rate of about 2.5 feet per year in the Sparta aquifer are indicated. For the two northern most measured wells,V029 and W069, water levels declined at a rate of about 3.5 to more than 4 feet per year, respectively; these were the highest calculated rates of water-level decline for the measured wells in the Sparta aquifer. The lowest rates of water-level decline were calculated for wells in the Cockfield aquifer (HI55, HI96 and N092) and range from about 0.5 to 1.5 feet per year. Table 1. Data for selected wells, Jackson, Mississippi, area [Altitude in feet; USGS, U.S. Geological Survey] Well Latitude Longitude Altitude Landnet Location Listed owner H023 322304 900850 315 T. 06 N., R. 01 E., Sec. 12 H155 321951 901058 330 T. 06 N., R. 01 E., Sec. 27 H160 322243 900739 305 T. 06 N., R. 02 E., Sec. 07 H163 322223 901328 354 T. 06 N., R. 01 E., Sec. 08 H164 322212 900957 298 T. 06 N., R. 01 E., Sec. 11 H196 322003 900925 290 T. 06 N., R. 01 E., Sec. 25 M094 321454 901603 360 T. 05 N., R. 01W., Sec. 26 Ml 12 321422 901801 330 T. 05 N., R. 01 W., Sec. 28 N092 321752 901026 271 T. 05 N., R. 01 E., Sec. 02 V029 322415 900944 355 T. 07 N., R. 01 E., Sec. 35 Kenneth Muse Miss. Geological Survey Colonial Country Club Tri State Brick Homewood Manor Miss. Ag Museum Jackson Jackson USGS Fairgrounds Tougaloo College W069 322514 900809 350 T. 07 N., R. 02 E., Sec. 30 Ridgeland