Edwards Aquifer Studies in Texas

The Edwards aquifer in the Balcones fault zone of southcentral Texas is one of the most permeable and most productive aquifers in the world. The competition for ground water from the Edwards aquifer has created some controversial water issues in central Texas. Designated a sole-source aquifer in the San Antonio and Austin areas by the U.S. Environmental Protection Agency (2003), the aquifer is critical to farming and ranching economies west of San Antonio and recreational economies northeast of the city.  Comal and San Marcos Springs and their effluent streams (rivers) support seven Federally listed endangered and one threatened species.

(Source: Conceptualization and Simulation of the Edwards Aquifer, San Antonio Region, Texas)

CURRENT DATA

Real-time USGS data

• USGS 08169000 Comal River at New Braunfels, TX
• USGS 08170500 San Marcos River at San Marcos, TX

Estimated Springflow data

• Streamflow and Springflow at Comal and San Marcos Rivers

EAA Groundwater Monitoring

• Edwards Aquifer Authority (EAA) Groundwater Level Monitoring Data

CURRENT SCIENCE PROJECTS

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Forecasting Models

Edwards Aquifer Groundwater Model Uncertainty Analysis

For more information, contact Linzy Foster

OTWSC is undertaking a 1.5-year study to assess parameter and predictive uncertainty in the Edwards Aquifer Authority MODFLOW Model using both linear and non-linear techniques. The Edwards Aquifer Authority (EAA) has recently (2017) updated a numeric groundwater model based on the work of Lindgren and others (2004) and updated by HDR (2011); the model simulates the period from 2001 to 2015 and the drought of record (1947-1958).

Contacts: Linzy Foster

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Geology

Hydrogeologic Mapping in Hays County

For more information, contact Ryan Banta

The Texas Water Development Board classifies the karstic Edwards and Trinity aquifers as major sources of water in south-central Texas. To effectively manage the water resources in the area, detailed maps and descriptions of the geology framework and hydrostratigraphic units of the aquifers in Hays County, Tex. are needed. In 2016 and 2018, OTWSC, in cooperation with the Edwards Aquifer Authority, mapped geologic framework and hydrostratigraphy of the Edwards and Trinity aquifers within Hays County, Tex. at 1:24,000 scale.

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Recharge Zone

Edwards Aquifer Recharge Zone Surface-water and Groundwater Interaction

For more information, contact Stephen Opsahl

The effects of urbanization across the recharge zone in Bexar County and potential impact on the water quality in the Edwards aquifer is a topic of specific concern for the City of San Antonio. OTWSC is simultaneously collecting water-quality data from surface-water runoff sites and paired shallow groundwater wells within the recharge zone of the Edwards aquifer to better characterize the water quality connection between surface water and groundwater. 

Edwards Aquifer Recharge Zone Monitoring Network

For more information, contact Stephen Opsahl

OTWSC is implementing a more complete and integrated monitoring network for the Edwards aquifer. More comprehensive and integrated information will improve the understanding of aquifer water quality and establish a baseline for measuring future water-quality changes.

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Water Quality

National Water-Quality Assessment Project in Texas

For more information, contact Marylynn Musgrove or Patricia Ging

Since 1992, NAWQA has been a primary source of nationally consistent data and information on the quality of the Nation’s streams and groundwater. Data and information obtained from objective and nationally consistent water-quality monitoring and modeling activities provide answers to where, when, and why the Nation’s water quality is degraded and what can be done to improve and protect it for human and ecosystem needs. For NAWQA’s third decade (2013–23), a new strategic Science Plan has been developed that describes a strategy for building upon and enhancing the USGS’s ongoing assessment of the Nation’s freshwater quality and aquatic ecosystems.