Natural sources of salinity in the Brazos River, Texas with particular reference to the Croton and salt Croton Creek basins

Abstract

The average daily load of the Brazos River at Possum Kingdom Reservoir is about 2,800 tons of dissolved solids, of which 1,000 tons is chloride. More than 85 percent of the chloride load is contributed by the Salt Fork Brazos River, and more than 50 percent of the chloride load of the Brazos River originates from salt springs and seeps in Croton and Salt Crotdn Creeks, which are tributaries of Salt Fork Brazos River. The rest of the chloride is contributed from many small sources. The average daily chloride load of Croton Creek is 70 tons, much of which is carried during periods of flood runoff. The average daily chloride load of Salt Croton Creek is about 480 tons. Of this total, 330 tons is contributed by the base flow, which ranges from 0.5 to 2 cubic feet per second. The principal areas of salt springs and seeps in the Croton Creek basin are Hot Springs and Short Croton Salt Flats in northeastern Kent County. In the Salt Croton Creek basin, saline water is discharged in Dove Creek Salt Flat, Dove Creek near Dove Creek Salt Flat, and three small salt flats on Haystack Creek, all in southwestern King County and northwestern Stonewall County. Salt springs and seeps discharge from the rocks of the Whitehorse Group undifferentiated in the Croton Creek basin, and from the upper part of the Dog Creek Shale of the Pease River Group in the Salt Croton Creek basin. Both groups are of Permian age. The water that is discharged by springs and seeps in the Croton Creek basin is derived from the infiltration of precipitation and seepage from streams in the Duck Creek basin. The source of the water that discharges in the Salt Croton basin is not known. The salt load contributed to the Brazos River by the springs and seeps can be reduced, although the volume of salt water for disposal probably cannot be reduced or eliminated. Collecting and disposing of the base flow of Salt Croton Creek would reduce the salt load of the Brazos River by 30 percent; disposal of the total flow of Salt Croton Creek would reduce the salt load by 45 percent. The salt water may be disposed of by impounding it in reservoirs for evaporation or by injecting it underground through oil wells, oil tests, or wells drilled for saltwater disposal. Sediments in which the salt water possibly could be injected underlie the. Dove Creek Salt Flats at depths of less than 7,000 feet.