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Castro and and Parmer Counties, with an estimated 700,000 acres under irrigation, are two of the leading agricultural counties in Texas. This report summarizes irrigation data collected by the U.S. Geological Survey at 64 randomly-selected sites as part of a study to better define the relationship between pumpage for irrigation and return flow to the High Plains aquifer from applied water (irrigat

Hydro!ogic investigations of urban watersheds in Texas were begun by the U.S. Geological Survey in 1954. Studies are now in progress in the Austin and Houston areas, and have been completed in the Dallas-Fort Worth and San Antonio areas. The U.S. Geological Survey, in cooperation with the city of Houston, began studies in the Houston metropolitan area in 1964. The program was expanded in 1968 to i

Hydrologic investigations of urban watersheds in Texas were begun by the U.S. Geological Survey in 1954. Studies are now in progress in Austin, and Houston. Studies have been completed in the Dallas, Fort Worth, and San Antonio areas. The Geological Survey, in cooperation with the Texas Department of Water Reources, began hydrologic studies in the Austin urban area in 1954. In cooperation with the

The Edwards-Trinity regional aquifer system supplies more than 0.78 million acre-feet per year (700 million gallons per day) of water for central Texas and small adjacent parts of southeast Oklahoma and southwest Arkansas. The system consists of three major aquifers and at least three minor aquifers in predominantly Cretaceous rocks, which together have an areal extent of about 80,000 square miles

Significant upward trends in dissolved-solids concentrations were detected with the Seasonal Kendall Test for trends at three stations in the upper basin during the study period. The increases exceeded 270 milligrams per liter per year at two stations and 165 milligrams per liter per year at the third station. The composition of dissolved constituents in the Colorado River basin changes from predo

Hydrologic Accounting Unit 120301 is located in north-central Texas and includes that part of the Trinity River basin upstream from the National Stream Quality Accounting Network station 08062700, Trinity River at Trinidad, Texas. Normal annual precipitation ranges from about 28 inches in the western part of the basin to almost 40 inches in the eastern part. The population of the upper Trinity Riv

The effects of urbanization on flood peaks in streams in the Austin metropolitan area were studied in two separate analyses. In the first analysis, annual peak discharge records at 13 streamflow-gaging sites were used to compute a recorded flood frequency relation for each site. Rainfall and streamflow data for 10 to 20 storms for each of these sites were used to calibrate a rainfall-runoff model

Twenty-seven geohydrology sections illustrate structural and stratigraphic relationships within the 180-mi-long Edwards aquifer. These sections were used to interpret the location of barriers within the Edwards aquifer. The sections are oriented generally south-southeast, which is approximately normal to both the east-northeast trending Edwards aquifer and the strike of the major faults of the Bal

Urban development over the Edwards aquifer in the Austin, Texas, area has caused concerns about the availability and quality of water in the aquifer. The study area, the Edwards aquifer that discharges to Barton Springs, includes parts of Travis and Hays Counties and extends from the city of Kyle to the Colorado River. A large part of the aquifer lies within the Austin metropolitan area one of the

The salinity front, locally known as the "bad-water" line, in the Edwards aquifer separates the freshwater from the salinewater and occurs where the aquifer is confined. The concentration of dissolved solids of the salinewater at the salinity front is 1,000 milligrams per liter. The concentration of dissolved solids in water within the freshwater zone of the aquifer usually ranges from 250 to 350

The surface-water resources of the United States, the focal point for this National Water Summary, are extensively developed and managed to provide water supplies, hydroelectric power, navigation, recreational opportunities, and sufficient instream flows to maintain fish and wildlife habitats and adequate water quality. Surface water represents 77 percent of the Nation's total freshwater withdrawa