Publications

The U.S. Geological Survey is conducting an assessment of water quality in the Trinity River Basin as part of the National Water-Quality Assessment Program. During the planning phase of this study, existing information on nutrients and suspended sediment was compiled and analyzed. A total of about 5,700 water-quality samples were analyzed from local, State, and Federal agencies. Of these, about 4,

Fifty-four major streams discharging directly to the Gulf of Mexico and having drainage areas exceeding 200 square miles were identified in the United States. Forty-four U.S. Geological Survey streamflow-gaging stations along the Gulf of Mexico with at least 40 years of daily streamflow data also were identified. These stations include most of the major streams and comprise 95 percent of the drain

Annual mean streamflow and annual minimum and maximum daily mean streamflows were compared with associated annual index precipitation for sites on the main channels and tributaries of four major rivers that discharge directly into the Gulf of Mexico. Long- and short-term precipitation trends were identified for selected streamflow stations with at least 40 years of record. Long-term temporal trend

All of the hydrogeologic subdivisions within the Edwards aquifer outcrop in Hays County have some porosity and permeability. The most porous and permeable appear to be hydrogeologic subdivision VI, the Kirschberg evaporite member of the Kainer Formation; hydrogeologic subdivision III, the leached and collapsed members, undivided; and hydrogeologic subdivision II, the cyclic and marine members, und

The U.S. Geological Survey, in cooperation with the Texas Department of Transportation, conducted a study of extreme flood potential for Texas. Potential extreme peak discharges, derived from the relation between documented extreme peak discharges and their contributing drainage areas, can provide valuable information concerning the maximum expected peak discharge that could occur at a stream site

Geologic sections showing the subsurface delineation of approximately 100 Stratigraphic units composing the Mesozoic and Cenozoic Eras illustrate the interrelation of these units across most of the Gulf Coastal Plain of Texas. The geologic names that constitute the nomenclature have been published, and the vast majority are approved for use by the U.S. Geological Survey. Four dip sections and four

The U.S. Geological Survey's investigations of the water resources of Texas are conducted in cooperation with the Texas Water Development Board, river authorities, cities, counties, U.S. Army Corps of Engineers, Bureau of Reclamation, International Boundary and Water Commission, and others. Investigations are under the general direction of R.O. Hawkinson, District Chief, Texas District. The addres

The Edwards aquifer, which is the sole source of water for the city of San Antonio, is one of the most permeable and productive carbonate aquifers in the United States. The aquifer is composed of extensively faulted, fractured, and cavernous limestone and dolomite of Early Cretaceous age lying within the Balcones fault zone a series of normal en echelon strike faults that separate the Edwards Plat

A consistent, basin-wide set of data for streams in the Trinity River Basin is necessary to provide a baseline for current conditions, to compare with historical data, and to provide a reference for future studies by the National Water-Quality Assessment (NAWQA) Program. In addition, the basin-wide surveys begin the process of addressing the cause-effect relation for water quality in the basin. Ef

One water-quality monitoring site was established on Whites Bayou, at the downstream end of the study area. Sampling began in March 1994 and will continue for 1 year. Sampling frequency ranges from four times per month in May and June to once per month in July. Stream-stage measurements were made three times per week from April to September. Field measurements during sampling include stream stage

The Trinity River Basin study-unit assessment began in October 1991, with 2 years dedicated to planning, analyzing existing information, and designing data-collection networks, surveys, and studies. Then, a 3-year intensive data-collection program was initiated. The assessment followed guidelines provided by the National Water-Quality Assessment (NAWQA) Program National Synthesis team and consider

The Trinity River Basin study-unit assessment began in October 1991, with 2 years dedicated to planning, analyzing existing information, and designing data-collection networks, surveys, and studies. Then, a 3-year intensive data-collection program was initiated. The assessment followed guidelines provided by the National Water-Quality Assessment (NAWQA) Program National Synthesis team and consider