Geology and ground-water resources of the Lufkin area, Texas

This report covers Angelina County, Texas, of which Lufkin is the county seat, and parts of Nacogdoches and other adjacent counties. The area is underlain by a series of sands, clays, and shales of Eocene age that dip, in general, southward at an angle a little greater than that of the land surface, which also slopes southward, thus creating favorable artesian conditions. The formations cropping out in the area from north to south are the Wilcox group undifferentiated, the Carrizo sand, the Mont Selman formation, consisting of the Reklaw member, the Queen City sand member, and the Weches greensand member, the Sparta sand, the Cook Mountain and Yegua formations, and the Jackson group undifferentiated. Small supplies of potable water may be obtained from shallow wells in the outcrop areas of most of these formations. Only three of the formations appear to be likely to yield large supplies of water to wells, and in these the water is under sufficient artesian pressure in most places to cause wells to flow. The Yegua formation yields large amounts of water to some wells in the vicinity of Lufkin. However, the water is moderately mineralized and is not acceptable for municipal use except after dilution with surface water and treatment to reduce mineralization. Moreover, most of the wells in this formation yield only small quantities of water, which is highly mineralized. The Sparta sand appears to be likely to yield large supplies of water to wells throughout the northern part of Angelina County. The water, however, is moderately to highly mineralized and cannot be used for purposes that require water of good quality. The Carrizo sand promises to yield large quantities of water low in mineralization in northern Angelina County and southern Nacogdoches County. Computations indicate that the present southward flow through the formation is about 2,750,000 gallons a day, but pumping from wells and thus increasing the hydraulic gradient would greatly increase the flow. Considerable amounts of water will also be released from storage in the formation after pumping begins.