Geologic and Hydrogeologic Framework of Regional Aquifers in the Twin Mountains, Paluxy, and Woodbine Formations Near the SSC Site, North-Central Texas

Abstract

Water-utility districts and many municipalities in North-Central Texas recently obtained as much as 100 percent of their water supply from deep regional aquifers in Cretaceous formations. Use of groundwater from the aquifers during the past century has resulted in water-level declines of as much as 850 ft (259 m), especially in Dallas and Tarrant Counties. Future water-level changes will depend on the amount of groundwater produced to help meet growing water-supply needs for municipalities, industries, and agriculture throughout North-Central Texas. It is probable that a significant part of the increased water demand will be met by groundwater although at less than historic rates. The objective of this study was to develop a predictive tool for studying the effect of future groundwater production from regional aquifers in North-Central Texas. To do this, we reviewed the history of groundwater development, hydrogeology of the regional aquifers, and constructed numerical models of groundwater flow. A cross-sectional model of both aquifers and confining layers was used to evaluate model boundary conditions and the vertical hydrologic properties of the confining layers. Results and insights from the cross-sectional model were used in a three-dimensional simulation of groundwater flow in the deep aquifers. The layers of the regional confining system were not explicitly included in the three-dimensional model. Hydrogeologic properties were assigned on the basis of aquifer test results and stratigraphic mapping of sandstone distribution in the aquifer units.Bureau of Economic Geolog