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

Water-utility districts and 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 800 ft (243.8 m) in Dallas and Tarrant Counties. Future continued water-level decline throughout North-Central Texas will depend on the amount of groundwater produced to help meet increased water-supply needs for municipal, industrial, and agricultural growth. It is probable that a significant part of the increased water demand will be met by groundwater.

The objectives of this study were to develop a hydrologic model of the complex interrelations among aquifer stratigraphy, hydrologic properties, and groundwater availability and, given expected patterns of future groundwater demand, to predict water-level changes in the regional aquifers that underlie North-Central Texas. 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 a regional confining system were not explicitly included in the three-dimensional model. Hydrogeologic properties were assigned based on aquifer test results and stratigraphic mapping of sandstone distribution in the aquifer units.