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This report presents data and informat ion, and indicates other sources of data, on water level s, recharge, discharge, spec ifi c capacity, well yields, and aquifer tests for the Edwards aquifer in the Sa n Antonio area, Texas.
This report presents hydrochemical data that was collected as part of the investigations of the Edwards aquifer in the San Antonio area, Te xas, during 1970-78 and indicates other sources of available data. The report includes the results of chemical analyses of 159 water samples from 123 well s and springs; tritium analyses for 242 water samples from 120 wells and springs; isotope and redox-potential analyses of 31 water samples from wells, springs, and streams; and calculated dissolved carbonate, partial C02 pressures, and saturation indices of selected minerals in 98 water samples from 81 wells, springs, and streams. The water types and hydrochemical facies are given for six zones of the aquifer.
The concentrations of dissolved solids, chloride, and sulfate in Livingston Reservoir on the Trinity River in southeastern Texas usually average less than 250 mg/l (milligrams per liter), 40 mg/l, and 50 mg/l, respectively. The water is usually hard or moderately hard (61 to 180 mg/l as calcium carbonate). The concentrations of principal dissolved constituents in the reservoir are usually maximum during summer and fall when evaporation is high and inflow is low. Thermal stratification of the reservoir usually begins in March and persists until September or October. Neither the seasonal variation of dissolved constituents in inflow to the reservoir nor thermal stratification has resulted in significant stratification of the principal dissolved constituents. However, thermal stratification has resulted in significant seasonal and areal variations of dissolved oxygen, which results in higher concentration of dissolved iron, dissolved manganese, total phosphorus, and total inorganic nitrogen. Oxygen utilized in the stabilization of unoxidized material from upstream sources, decaying algae, and pre-existing organic material along the bottom of the reservoir is not replaced during periods of summer stagnation; and water below depths of 25 to 35 feet (8 to 11 meters) usually contains less than 1.0 mg/l dissolved oxygen. During periods of summer stagnation, reducing conditions often result in the solution of iron and manganese from bottom sediments in the deep parts of the reservoir. At site A C , a deep site near Livingston Dam, dissolved-iron concentrations in water near the bottom of the reservoir during summer have ranged from 80 to 2,300 μg/l (micrograms per liter) and have averaged about 750 μg/l. The concentrations of dissolved manganese in water near the bottom of the reservoir at this site during summer have ranged from 230 to 4,700 μg/l and have averaged about 2,600 μg/l. Water near the surface of the reservoir throughout the year and water near the bottom during periods of winter circulation usually contain less than 100 μg/l of dissolved iron and 100 μg/l of dissolved manganese. The concentrations of total phosphorus and inorganic nitrogen in water near the bottom at deep sites near Livingston Dam are usually maximum during periods of summer stagnation when decay of aquatic organisms and chemical reduction of bottom sediments release phosphorus and nitrogen to the water. The concentrations of phosphorus in the bottom stratum of water at site A C average about 2.0 mg/l. The concentrations of inorganic nitrogen in the bottom and surface strata at this site during summer average about 4.0 mg/l and 0.1 mg/l, respectively. Seasonal temperature and dissolved oxygen cycles have resulted in significant quantities of dissolved iron, dissolved manganese, total phosphorus, and total inorganic nitrogen being trapped and recycled within the reservoir.
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The collection of hydrologic data by the U.S. Geological Survey in the Mountain Creek watershed began on March 9, 1925, with the establishment of a stream-gaging station located about 2.5 miles upstream from the present site of Mountain Creek Lake Dam. The stream-gaging station was discontinued on July 5, 1933. Daily streamflow records obtained at this site are published in the annual series of Geological Survey Water-Supply Papers beginning in 1925. Monthly and yearly summaries are published in Water-Supply Paper 1312. In October 1960, the Geological Survey resumed collection of hydrologic data in the Mountain Creek watershed by establishing three stream-gaging stations and one reservoir-content station. The data-collection sites are on Mountain Creek near Cedar Hill, Walnut Creek near Mansfield, Mountain Creek at Grand Prairie, and Mountain Creek Lake near Grand Prairie (fig. 1). In October 1970, the Geological Survey assumed operation of the stage station Mountain Creek near Duncanville (fig. 1). Water-quality data for the 1977 water year for sites in the study area are presented in downstream order along with the streamflow data in the section "Compilation of data." A complete tabulation of data, including laboratory analyses, for the 1977 water year for the Trinity River basin is given in Water resources data for Texas, TX-77-1, 1977. The purpose of this report is to compile the records of streamflow and reservoir content for the year into a form which facilitates their use in detailed analyses of the Mountain Creek hydrologic system. This report contains basic-hydrologic data for the 1977 water year (Oct. 1, 1976-Sept. 30, 1977). Assistance in the form of funds or services was provided by the Texas Department of Water Resources and the Dallas Power and Light Company.
This report, which was prepared in cooperation with the City of Hoston, the Harris-Galveston Coastal Subsidence District, and the Texas Department of Water Resources, presents data on water-level changes in the Chicot and Evangeline aquifers.
This report, which was prepared in cooperation with the cities of Houston and Galveston, the Harris-Galveston Coastal Subsidence District, and the Texas Department of Water Resources, presents data on land-surface subsidence for 1906-78, 1943-78, and 1973-78 (Figs. 1-3).
The purpose of this report, which was prepared in cooperation with the City of Houston, the Harris-Galveston Coastal Subsidence District, and the Texas Department of Water Resources, is to show the altitudes of water levels in wells in the Chicot and Evangeline aquifers in the Houston, Texas, metropolitan area. The maps are based on water-level measurements in 1981 in about 500 wells.
The purpose of this report, which was prepared in cooperation with the City of Houston, the Harris-Galveston Coastal Subsidence District, and the Texas Department of Water Resources, is to show the altitudes of water levels in wells in the Chicot and Evangeline aquifers in the Houston, Texas, metropolitan area. The maps are based on water-level measurements in spring of 1984 in about 500 wells.
The purpose of this report, which was prepared in cooperation with the cities of Houston and Galveston, the Harris-Galveston Coastal Subsidence District, and the Texas Department of Water Resources, is to show the altitudes of water levels in wells in the Chicot and Evangeline aquifers in the Houston, Texas, metropolitan area. The maps are based on water-level measurements in 1977 and 1978 in about 550 wells.
The purpose of this report, which was prepared in cooperation with the city of Houston, the Harris-Galveston Coastal Subsidence District, and the Texas Department of Water Resources, is to show the altitudes of water levels in wells in the Chicot and Evangeline aquifers in the Houston, Texas, metropolitan area. The maps are based on water-level measurements in 1979 and 1980 in about 500 wells. Both the Chicot and Evangeline aquifers are composed of several sand layers with different potentiometric surfaces. These maps, however, show approximations of single potentiometric heads. Maps showing the altitudes of water levels have been published in many reports on ground-water development in the Houston area, the most recent of which (Gabrysch, 1979) presented maps of the altitudes of potentiometric surfaces for 1977 and 1978.