Groundwater Availability in the Lower Arkansas River Basin

The  lower Arkansas and Walnut River basins in Kansas are located in Sedgwick, Butler,  Sumner, and Cowley counties in the sourth Kansas, which includes Wichita city, the largest city in Kansas. This area are experiencing rapid population growth and consequently placing increased demands on surface and groundwater resources. The quantity and quality of water available in the lower Arkansas and Walnut River basins will become crucial if population and water use continue to increase as projected. The population and water use in the area are estimated to have increased by about 19 and 8 percent, respectively, between 1985 and 1995 (population was about 414,000 in 1985 and about 491,000 in 1995; water use was about 26.5 million gallons per year (Mgal/yr) in 1985 and about 28.7 Mgal/yr in 1995 and are projected to increase by another 13 and 21 percent, respectively, between 1995 and 2010. Much of the increase in population and water use has and is projected to occur in and near Wichita. This area accounted for, and is projected to continue to account for, about 60-65 percent of the population and about 65-70 percent of the water use in the basin. The Kansas Department of Agriculture, Division of Water Resources (DWR), which is charged with the beneficial allocation of the water resources in Kansas, is concerned about these increased and projected demands because of the limited water resources available in the lower Arkansas and Walnut River basins.

DWR has recognized that the currently available hydrologic information for this area is not sufficient for it to effectively apply existing water management and regulatory measures to protect and allocate the limited water resources of the lower Arkansas and Walnut River basins, especially during periods of drought. Information DWR needs includes better delineation of the aquifers in the area, improved estimates of groundwater recharge, a better understanding of the groundwater flow conditions in the area, the interaction of the ground and surface waters, and the effect of these hydrologic conditions on the availability and quality of the surface and groundwaters. Acquisition of this information will also enable DWR to meet the second of the 16 long-range objectives of the Kansas Water Plan endorsed by the Kansas Water Authority (July 8, 1999). The second Kansas Water Plan objective is ôBy 2010, over 95 percent of public water suppliers dependent upon surface water supplies and alluvial aquifers shall have a source of supply sufficient to meet their needs during a drought having a two percent chance of occurrence.Ý

The objectives for this study are:

1. Delineate aquifers and their characteristics in the study area;

2.  Develop a tool for DWR to compute sustainable yield in upland areas away from the river valleys;

3.  Determine the effects of well pumping, and groundwater pits on ground and surface water supplies; and

4. Determine areas vulnerable to adverse changes in groundwater quality.