Ground-water resources of Rusk County, Texas

Abstract

Fresh to slightly saline water is available in most parts of Rusk County, which is located in the Piney Woods region of northeast Texas. The Wilcox aquifer, which underlies the entire county, was the source of most of the ground water withdrawn during 1980. Other units capable of yielding fresh ground water are the Carrizo, Queen City, and Sparta aquifers and the Reklaw Formation. About 5.4 million gallons per day (20,440 cubic meters per day) of ground water was used for all purposes during 1980. Of this amount, about 78 percent was used for public supply, 10 percent for mining, 8 percent for industrial purposes, and 4 percent for rural domestic use. Water levels have declined extensively at the city of Henderson, which used about 38 percent of all ground water consumed in Rusk County. Generally, the ground water is of acceptable quality. Water in some of the near-surface beds and some of the deeper sands in the Wilcox aquifer may have become mineralized because of oilfield operations. Ground-water contamination by oilfield brines at Henderson Oil Field has been documented. Two separate instances of streamflow contamination at Striker Creek and Henderson Oil Field have been documented. Moderate amounts of ground water are available for development. The amount that is available perennially is not known, but it is greater than that being withdrawn. Assuming a hydraulic gradient of about 8 feet per mile (1.5 meters per kilometer), at least 12 million gallons per day (45,420 cubic meters per day) of fresh ground water is being transmitted through the Wilcox and about 3 million gallons per day (11,350 cubic meters per day) through the Carrizo. About 20 million acre-feet (24,660 cubic hectometers) of freshwater is available from storage in the Wilcox and about 4 million acre-feet (4,930 cubic hectometers) from storage in the Carrizo. Additional amounts of slightly saline water are available from the major aquifers. Smaller but undetermined amounts of fresh ground water are available from the Sparta and Queen City aquifers and from the Reklaw Formation. Properly constructed wells in the Wilcox and Carrizo aquifers can be expected to yield more than 500 gallons per minute (32 liters per second) if the wells are properly spaced. Development of additional resources around the city of Henderson and the Mount Enterprise Fault System should be considered cautiously because of the probability of saltwater encroachment. Ground water in other parts of the county is practically undeveloped. Some mineralization of ground water is due to natural causes. Other mineralization of ground water is due to contamination. A program needs to be initiated to determine the extent and cause of mineralization that has taken place in freshwater sands. Water-quality data is needed at Henderson in order to monitor saltwater encroachment.