Oklahoma Water Science Center
Central Oklahoma (Garber-Wellington) Aquifer Study
The Central Oklahoma aquifer, also referred to as the Garber-Wellington aquifer, underlies about 3,000 square miles in central Oklahoma, where the aquifer is used for municipal, industrial, commercial, agricultural, and domestic water supplies. With the exception of Oklahoma City, all the major communities in central Oklahoma rely either solely or partly on groundwater from this aquifer. In addition to public water supply wells, more than 20,000 homeowners use groundwater for household or lawn use (domestic use). New development is moving into rural areas, resulting in increased groundwater withdrawals from areas that previously had not been developed. As new areas are developed for groundwater supply increased water withdrawals may result in decreases in surface water, such as streamflow in Deep Fork and Little River and flows into Lake Arcadia, Lake Draper, and Lake Thunderbird.
The 1973 Oklahoma water law requires the Oklahoma Water Resources Board (OWRB) to conduct hydrologic investigations of the State’s aquifers (termed “groundwater basins”), and to determine amounts of water that may be withdrawn by permitted water users. At the beginning of the investigation (2009), the maximum annual yield had not been determined for the Garber-Wellington aquifer. Until the determination is made, water users are issued a temporary permit for 2 (acre-feet/acre)/year. OWRB typically uses groundwater flow models as a tool to determine the maximum annual yield. The models take into consideration the rate of natural recharge, total discharge, and aquifer transmissivity.
The objective of the study was to provide information that will enable the OWRB to determine the maximum annual yield of the Garber-Wellington aquifer. The primary information needed to determine the maximum annual yield includes projected effects of groundwater withdrawals on (1) water levels in the aquifer, (2) the volume of water in storage in the aquifer, and (3) groundwater discharge to streams that flow across the aquifer. Transient groundwater flow models (MODFLOW) were used to determine the projected effects of several proposed management plans and development scenarios.