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Person

Stephen P Opsahl

Hydrologist
Email: sopsahl@usgs.gov
Office Phone: 210-691-9247
Fax: 210-691-9270
ORCID: 0000-0002-4774-0415

Location
5563 DeZavala Road
Suite 290
San Antonio , TX 78249
US
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The U.S. Geological Survey (USGS), in cooperation with the City of South Padre Island, Texas, deployed an acoustic Doppler current profiler (ADCP) to collect current velocity, wave height, and directional data in the lower Laguna Madre adjacent to South Padre Island, Texas. From July 19, 2022, through January 9, 2023, these data were collected at a site near South Padre Island (USGS station number 260551097100901) by using an up-looking acoustic doppler current profiler (ADCP) mounted on the bottom of the lower Laguna Madre. Raw data were collected at a frequency of 2 hertz (Hz); reported values were computed as the average of the processed data values for 60-minute intervals. All times are represented in Coordinated...
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Continuous monitoring and discrete water-quality sampling were coupled in a karst aquifer to assess drivers and timescales of water-quality change. Water-quality data included environmental tracers of groundwater age (tritium [3H], tritiogenic helium-3 [3He-trit], sulfur hexafluoride [SF6], carbon-14 [14C], and radiogenic helium-4 [4He-rad]). All water quality data is available from the U.S. Geological Survey NWIS database (U.S. Geological Survey, 2019). Groundwater ages were estimated by calibration of environmental tracers to lumped parameter models of groundwater age for multiple samples collected at six groundwater wells using the program TracerLPM (Jurgens and others, 2012). The final estimates for mean groundwater...
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Groundwater samples collected from the Edwards aquifer in south-central Texas were analyzed for water-quality data to assess aquifer susceptibility to contaminants. Water-quality data included environmental tracers of groundwater age (tritium, tritiogenic helium-3, sulfur hexafluoride, carbon-14, and radiogenic helium-4), calibrated to lumped parameter models (LPMs). Groundwater samples were collected from monitoring wells, domestic-supply wells, and public-supply wells during 2017 and 2018. This data release includes seven tables detailing these data. The final estimates for mean groundwater ages determined for samples from 65 wells ranged from 4 years to 45,400 years, with a median of 25 years. Table 1 provides...
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The extensive development of oil and natural-gas resources in south Texas during the past 10 years has led to questions regarding possible environmental effects of processes associated with oil and natural-gas production, in particular the process of hydraulic fracturing, on water and other natural resources. Part of the lower San Antonio River watershed intersects an area of oil and natural-gas production from the sedimentary rocks that compose the Eagle Ford Group. The rapid expansion of infrastructure associated with oil and natural-gas production increases potential pathways for inorganic and organic contaminants to enter surface-water systems. The U.S. Geological Survey, in cooperation with the San Antonio...
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Located in south-central Texas, the Geronimo Creek and Plum Creek watersheds have long been characterized by elevated nitrate concentrations. From April 2015 through March 2016, an investigation was done by the U.S. Geological Survey, in cooperation with the Guadalupe-Blanco River Authority (GBRA) and the Texas State Soil and Water Conservation Board (TSSWCB), to assess nitrate (as nitrogen) concentrations and to document possible sources of elevated nitrate as nitrogen in these two watersheds. Water-quality samples were collected from 20 groundwater, spring, and stream sites across the two watersheds, along with precipitation samples and wastewater treatment plant (WWTP) effluent samples from the Plum Creek watershed....
Categories: Data; Tags: Buda, Caldwell County, Caldwell County, Comal County, Geronimo Creek, All tags...
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