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| Carrizo-Wilcox Aquifer | |
|---|---|
| Name | Carrizo-Wilcox Aquifer |
| Location | Texas, Louisiana, Arkansas |
| Type | Aquifer |
Carrizo-Wilcox Aquifer The Carrizo-Wilcox Aquifer underlies parts of Texas, Louisiana, and Arkansas and provides groundwater for municipal, agricultural, and industrial use. It is a major component of regional water resources connected to river systems such as the Brazos River, Trinity River (Texas), and Sabine River, and interacts with surface water bodies like Lake Livingston and Toledo Bend Reservoir. Management involves federal and state agencies including the United States Geological Survey, Texas Water Development Board, and Louisiana Department of Environmental Quality.
The aquifer spans large portions of eastern Texas, western Louisiana, and southern Arkansas, extending beneath counties such as Harris County, Texas, Bexar County, Texas, Montgomery County, Texas, and Jefferson County, Texas. It lies across physiographic provinces including the Gulf Coastal Plain and near formations like the Palo Duro Formation and Wichita Formation. Major cities overlying the aquifer include Houston, San Antonio, Austin, Beaumont, and Lufkin, which rely on its wells near landmarks such as Sam Houston National Forest and Big Thicket National Preserve.
Geologically, the aquifer consists of Tertiary sandstones and conglomerates interbedded with clays and shales, correlated with units recognized in the Wilcox Group and the Carrizo Sand. Hydrogeologic studies by the United States Geological Survey and university programs at Texas A&M University, University of Texas at Austin, and Louisiana State University describe transmissivity and storativity influenced by porosity in sandstone layers. Recharge occurs through precipitation over recharge zones near the Edward Plateau margin and along outcrops adjacent to the Balcones Fault Zone and Ouachita Mountains. Groundwater flow gradients trend toward major drainages including the Neches River and Sabine River, with hydraulic connection considerations involving the Cenozoic stratigraphy and aquifers such as the Edwards Aquifer and Gulf Coast Aquifer.
Water quality varies spatially, with constituents monitored by the Environmental Protection Agency programs and state agencies. Constituents of concern include elevated concentrations of dissolved solids, iron, manganese, and regional salinity influenced by proximity to the Gulf of Mexico and natural brines. Contamination episodes have involved petroleum hydrocarbons from fields like the East Texas Oil Field, agrichemicals tied to croplands near Brazoria County, Texas and Wharton County, Texas, and anthropogenic nitrates evaluated in studies by University of Arkansas researchers. Legacy contamination from industrial facilities listed under Comprehensive Environmental Response, Compensation, and Liability Act sites and landfills near urban centers such as Beaumont, Texas and Lake Charles, Louisiana have prompted groundwater investigations. Monitoring networks coordinate with programs led by the National Aeronautics and Space Administration for remote sensing, and with research at the United States Environmental Protection Agency laboratories.
The aquifer supplies water for large municipal systems serving Houston suburbs, for irrigation in agricultural counties like Wharton County, Texas and Brazos County, Texas, and for industry in petrochemical corridors near Port Arthur, Texas and Beaumont-Port Arthur Metropolitan Statistical Area. Public utilities including the San Antonio Water System and regional districts draw from shallow and deep wells, and power plants such as those near Baytown, Texas use groundwater for cooling makeup. Seasonal droughts documented in records by the National Oceanic and Atmospheric Administration and Drought Monitor increase reliance on the aquifer, affecting allocations under interstate compacts involving Texas and Louisiana water users.
Management involves coordination among entities such as the Texas Water Development Board, Texas Commission on Environmental Quality, Louisiana Department of Natural Resources, and regional groundwater conservation districts including the Gulf Coast Water Authority and local Groundwater Conservation Districts of Texas. Regulatory frameworks reference state statutes like the Texas Water Code and federal statutes administered by the United States Environmental Protection Agency. Conservation programs align with initiatives from United States Department of Agriculture conservation practices, municipal water conservation plans from agencies in Houston and San Antonio, and incentive programs influenced by research from Texas A&M AgriLife Research. Augmentation and recharge projects have been proposed in coordination with the United States Army Corps of Engineers and regional watershed planning organizations.
Exploration and development trace to early well drilling in the 20th century during expansion of irrigation and the growth of cities such as Houston and San Antonio. Geological mapping by the United States Geological Survey and academic surveys at University of Texas at Austin and Louisiana State University clarified the Wilcox and Carrizo stratigraphy. Development accelerated alongside the discovery of the East Texas Oil Field and growth of the petrochemical industry in the Golden Triangle, Texas, prompting increased groundwater extraction for municipal and industrial use. Historic droughts, notably the 1950s North American drought episodes and more recent 2011 Texas drought, catalyzed policy shifts toward groundwater conservation and multidisciplinary studies by institutions including the Bureau of Reclamation and National Academies of Sciences, Engineering, and Medicine.