No abstract

The Sabine River basin has an abundant supply .of surface water of excellent quality. The basin area of 9,700 square miles receives an average of about 48 inches of rainfall per year, of which about 13 inches flows to the Gulf of Mexico. Variations in the chemical quality of the surface waters in the Sabine River basin are caused principally by areal differences in geology and runoff; but industrial influences, particularly the disposal of oilfield brines, affect the quality in limited areas. Water having the least dissolved solids is found in the lower part of the basin, where rainfall is greatest. Water having higher values of hardness are found in the area of Cretaceous limestone, chalk, and marl in the northwestern part of the basin. Chloride concentrations are generally low except where streams are polluted by oilfield brines and localized natural saline inflow. Existing reservoirs in the basin contain water of excellent quality, and water to be stored in proposed reservoirs should be excellent.

The kinds and quantities of minerals dissolved in the surface water of the Neches River basin result from such environmental factors as geology, streamflow patterns and characteristics, and industrial influences. As a result of high rainfall in the basin, much of the readily soluble material has been leached from the surface rocks and soils. Consequently, the water in the streams is usually low in concentrations of dissolved minerals and meets the U.S. Public Health Service drinking-water standards. In most streams the concentration of dissolved solids is less than 250 ppm (parts per million).The Neches River drains an area of about 10,000 square miles in eastern Texas. From its source in southeast Van Zandt County the river flows in a general southeasterly direction and empties into Sabine Lake, an arm of the Gulf of Mexico.In the basin the climate ranges from moist subhumid to humid, and the average annual rainfall ranges from 46 inches in the northwest to more than 52 inches in the southeast. Annual runoff from the basin has averaged 11 inches; however, runoff rates vary widely from year to year. The yearly mean discharge of the Neches River at Evadale has ranged from 994 to 12,720 cubic feet per second.The rocks exposed in the Neches River basin are of the Quaternary and Tertiary Systems and range in age from Eocene to Recent. Throughout most of the basin the geologic formations dip generally south and southeast toward the gulf coast. The rate of dip is greater than that of the land surface; and as a result, the older formations crop out to the north of the younger formations. Water from the outcrop areas of the Wilcox Group and from the older formations of the Claiborne Group generally has dissolved-solids concentrations ranging from 100 to 250 ppm; water from the younger formations has concentrations less than 100 ppm.The northern half of the basin has soft water, with less than 60 ppm hardness. The southern half of the basin has very soft water, usually with less than 30 ppm hardness.The chloride concentrations are less than 20 ppm in surface water in the southern half of the basin and usually range from 20 to 100 ppm in the northern half of the basin. Concentrations greater than 100 ppm are found only where pollution is occurring. Al A2 CONTRIBUTIONS TO THE HYDROLOGY OF THE UNITED STATESThe Neches River basin has an abundance of surface water, but uneven distribution of runoff makes storage projects necessary to provide dependable water supplies. The principal existing reservoirs, with the exception of Striker Creek Reservoir, contain water of excellent quality. Chemical-quality data for the Striker Creek drainage area indicate that its streams are affected by the disposal of brines associated with oil production. Sam Rayburn Reservoir began impounding water in 1965. The water impounded should prove of acceptable quality for most uses, but municipal and industrial wastes released into the Angelina River near Lufkin may have a degrading effect on the quality of the wate'r, especially during extended period...

Dissolved-solids data from 54 river basins for 1966-69 were used to compute the amount of dissolved material contributed to the oceans from the conterminous United States. The computations show that about 264,000,000 tons are discharged annually. The Gulf of Mexico receives the largest load, about 183,000,000 tons, of which about 15 7,000,000 tons are contributed by the Mississippi River. The Atlantic Ocean receives about 37,500,000 tons, and the Pacific Ocean about 43,400,000 tons.Average yearly yields range from 26 to 231 tons per square mile and average about 100 tons per square mile.