Allan K Clark
Hydrologist, Oklahoma-Texas Water Science Center
Education and Certifications
Master of Science, Geology (2002) University of Texas San Antonio
Bachelor of Science, Geology (1992) University of Texas San Antonio
Associates Degree, General Studies (1987) Victoria College
Affiliations and Memberships*
Professional Geoscientists License (#5877) The State of Texas
Honors and Awards
Bernold M. "Bruno" Hanson DEG Excellence of Presentation Award (2008) AAPG Annual convention
Thirty Years of Service award (2021) USGS
Science and Products
Karst Aquifers: Pacific Northwest Pseudokarst Aquifers
Karst Interest Group (KIG) Workshop
The Karst Interest Group’s (KIG) mission is to encourage and support collaboration and technology transfer among scientists working in karst areas. The KIG encourages cooperative studies between USGS Programs and Water Science Centers, and between USGS and other Federal agencies, State and local agencies, and universities.
The 9th USGS KIG Workshop will be October 22-24, 2024 in Nashville, TN.
Hydrogeology of the Edwards and Trinity Aquifers within Hays County
Geophysical analysis of the Salmon Peak Formation near Amistad Reservoir Dam, Val Verde County, Texas, and Coahuila, Mexico, March 2006, to aid in piezometer placement
Flow paths in the Edwards aquifer, northern Medina and northeastern Uvalde counties, Texas, based on hydrologic identification and geochemical characterization and simulation
Geologic Map of the Edwards Aquifer In Northern Medina and Northeastern Uvalde Counties, South-central Texas
Helicopter electromagnetic and magnetic survey data and maps, northern Bexar County, Texas
Geologic framework and hydrogeologic features of the Glen Rose Limestone, Camp Bullis Training Site, Bexar County, Texas
Geologic framework and hydrogeologic characteristics of the Edwards aquifer, Uvalde County, Texas
Vulnerability of ground water to contamination, Edwards Aquifer recharge zone, Bexar County, Texas, 1998
Geologic framework and hydrogeologic characteristics of the Edwards Aquifer outcrop, Medina County, Texas
Geologic framework of the Edwards Aquifer and upper confining unit, and hydrogeologic characteristics of the Edwards Aquifer, south-central Uvalde County, Texas
Science and Products
- Science
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Karst Aquifers: Pacific Northwest Pseudokarst Aquifers
Pseudokarst features such as lava tubes, fissures, open sinkholes, and caves, are extensive in some regions of the west. Some of the largest regions with this type of pseudokarst are located in the Pacific Northwest, including the Snake River area of Idaho, part of the Columbia Basalt Plateau in Washington and Oregon, and in the lava fields of northeastern California.Karst Interest Group (KIG) Workshop
The Karst Interest Group’s (KIG) mission is to encourage and support collaboration and technology transfer among scientists working in karst areas. The KIG encourages cooperative studies between USGS Programs and Water Science Centers, and between USGS and other Federal agencies, State and local agencies, and universities.
The 9th USGS KIG Workshop will be October 22-24, 2024 in Nashville, TN.
Hydrogeology of the Edwards and Trinity Aquifers within Hays County
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 geologic framework and hydrostratigraphic units of the aquifers in Hays County, Texas are needed. In 2016 and 2018, the Texas Water Science Center (TXWSC), in cooperation... - Data
- Maps
- Publications
Filter Total Items: 21
Geophysical analysis of the Salmon Peak Formation near Amistad Reservoir Dam, Val Verde County, Texas, and Coahuila, Mexico, March 2006, to aid in piezometer placement
Since 1992, numerous sinkholes have developed northwest of the Amistad Reservoir dam on the Rio Grande. Increases in the discharge of springs south of the dam, on the western side of the Rio Grande, in Coahuila, Mexico, have been documented. In 1995 the Mexico Section of the International Boundary and Water Commission (IBWC) completed a study of the western embankment (Coahuila, Mexico) of the damAuthorsGregory P. Stanton, Wade H. Kress, Andrew Teeple, Michael L. Greenslate, Allan K. ClarkFlow paths in the Edwards aquifer, northern Medina and northeastern Uvalde counties, Texas, based on hydrologic identification and geochemical characterization and simulation
The U.S. Geological Survey, in cooperation with the San Antonio Water System, conducted a 4-year study during 2001– 04 to identify major ground-water flow paths in the Edwards aquifer in northern Medina and northeastern Uvalde Counties, Texas. The study involved use of geologic structure, surfacewater and ground-water data, and geochemistry to identify ground-water flow paths. Relay ramps and assoAuthorsAllan K. Clark, Celeste A. JourneyGeologic Map of the Edwards Aquifer In Northern Medina and Northeastern Uvalde Counties, South-central Texas
The southern segment of the Edwards aquifer in south-central Texas is one of the most productive subsurface reservoirs of potable water in the world, providing water of excellent quality to more than a million people in the San Antonio region, where the Environmental Protection Agency (EPA) has declared it to be a sole-source aquifer (van der Leeden and others, 1990). Depending on the depositionalAuthorsAllan K. Clark, Jason R. Faith, Charles D. Blome, Diana E. PedrazaHelicopter electromagnetic and magnetic survey data and maps, northern Bexar County, Texas
No abstract available.AuthorsBruce D. Smith, Michael J. Cain, Allan K. Clark, David W. Moore, Jason R. Faith, Patricia L. HillGeologic framework and hydrogeologic features of the Glen Rose Limestone, Camp Bullis Training Site, Bexar County, Texas
The Glen Rose Limestone crops out over most of the Camp Bullis Training Site in northern Bexar County, Texas, where it consists of upper and lower members and composes the upper zone and the upper part of the middle zone of the Trinity aquifer. Uncharacteristically permeable in northern Bexar County, the Glen Rose Limestone can provide avenues for recharge to and potential contamination of the dowAuthorsAllan K. ClarkGeologic framework and hydrogeologic characteristics of the Edwards aquifer, Uvalde County, Texas
The Edwards aquifer in Uvalde County is composed of Lower Cretaceous carbonate (mostly dolomitic limestone) strata of the Devils River Formation in the Devils River trend and of the West Nueces, McKnight, and Salmon Peak Formations in the Maverick basin. Rocks in the Devils River trend are divided at the bottom of the Devils River Formation into the (informal) basal nodular unit. Maverick basin roAuthorsAllan K. ClarkVulnerability of ground water to contamination, Edwards Aquifer recharge zone, Bexar County, Texas, 1998
The Edwards aquifer, one of the most productive carbonate-rock aquifers in the Nation, is composed of the Kainer and Person Formations of the Edwards Group plus the overlying Georgetown Formation. Most recharge to the Edwards aquifer results from the percolation of streamflow loss and the infiltration of precipitation through porous parts of the recharge zone. Residential and commercial developmenAuthorsAllan K. ClarkGeologic framework and hydrogeologic characteristics of the Edwards Aquifer outcrop, Medina County, Texas
The hydrogeologic subdivisions of the Edwards aquifer outcrop in Medina County generally are porous and permeable. The most porous and permeable appear to be hydrogeologic subdivision VI, the Kirschberg evaporite member of the Kainer Formation; and hydrogeologic subdivision III, the leached and collapsed members, undivided, of the Person Formation. The most porous and permeable rocks of the DevilsAuthorsTed A. Small, Allan K. ClarkGeologic framework of the Edwards Aquifer and upper confining unit, and hydrogeologic characteristics of the Edwards Aquifer, south-central Uvalde County, Texas
The stratigraphic units of the Edwards aquifer in south-central Uvalde County generally are porous and permeable. The stratigraphic units that compose the Edwards aquifer in south-central Uvalde County are the Devils River Formation in the Devils River trend; and the West Nueces, McKnight, and Salmon Peak Formations in the Maverick Basin. The Balcones fault zone is the principal structural featureAuthorsAllan K. Clark, Ted A. Small
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government