The Edwards-Trinity aquifer, located in the Trans-Pecos and the Edwards Plateau areas, is composed of relatively flat-lying rocks that are generally exposed at the land surface. This aquifer is generally recharged by precipitation; water is mostly unconfined in the shallow parts of the aquifer and is confined in the deeper zones.
The rocks that compose the Edwards-Trinity aquifer are relatively flat-lying and are generally exposed at the land surface in the Trans-Pecos and the Edwards Plateau areas. The geologic formations that compose the Trinity and the Edwards aquifers generally are exposed in updip areas, but they dip eastward and southward beneath younger units and lie deep in the subsurface. The downdip boundary of each aquifer approximately coincides with the farthest updip extent of water that contains 10,000 milligrams per liter dissolved solids. The base of the aquifer slopes generally to the south and southeast. Most of the rocks that underlie the Edwards-Trinity aquifer are much less permeable than those that compose the aquifer and, thus, serve as a barrier to groundwater flow. Locally, however, the underlying rocks are permeable and are hydraulically connected to the Edwards-Trinity aquifer, thus extending the thickness of the flow system. The aquifer is generally recharged by direct precipitation on the land surface. Water is mostly unconfined in the shallow parts of the aquifer and is confined in the deeper zones.
Caves
Springs
Featured Studies and Datasets
Aquifer-scale studies and the datasets they produce are a key component to understanding how karst aquifers behave, and the quality of water within them.
- National Water-Quality Assessment, South-Central Texas — A program to describe the status and trends in water quality of a large, representative part of the Nation's surface-water and groundwater resources.
Additional Information
The following websites are additional sources of information about this aquifer:
- Texas Water Development Board: Springs Monitoring Program
- Edwards Aquifer Authority
- Barton Springs Edwards Aquifer Conservation District
- San Marcos Salamander Photos - U.S. Fish and Wildlife Service National Digital Library
- Barton Springs Salamander Photos - U.S. Fish and Wildlife Service National Digital Library
Below are other science projects associated with karst aquifers.
Karst Aquifers
Karst Aquifers: Arbuckle-Simpson Aquifer
Karst Aquifers: Basin and Range and Bear River Range Carbonate Aquifers
Karst Aquifers: Colorado Plateau Karst
Karst Aquifers: Edwards Balcones Fault Zone Aquifer
Karst Aquifers: Edwards-Trinity Plateau Aquifer
Karst Aquifers: Upper Floridan and Biscayne Aquifers
Karst Aquifers: Madison Aquifer
Karst Aquifers: Midwest Paleozoic Carbonate Aquifers
Karst Aquifers: New England Karst Aquifers
Karst Aquifers: Ozark Plateau Karst Aquifers
Karst Aquifers: Roswell Basin Aquifer
Karst Aquifers: Pacific Northwest Pseudokarst Aquifers
- Overview
The Edwards-Trinity aquifer, located in the Trans-Pecos and the Edwards Plateau areas, is composed of relatively flat-lying rocks that are generally exposed at the land surface. This aquifer is generally recharged by precipitation; water is mostly unconfined in the shallow parts of the aquifer and is confined in the deeper zones.
The rocks that compose the Edwards-Trinity aquifer are relatively flat-lying and are generally exposed at the land surface in the Trans-Pecos and the Edwards Plateau areas. The geologic formations that compose the Trinity and the Edwards aquifers generally are exposed in updip areas, but they dip eastward and southward beneath younger units and lie deep in the subsurface. The downdip boundary of each aquifer approximately coincides with the farthest updip extent of water that contains 10,000 milligrams per liter dissolved solids. The base of the aquifer slopes generally to the south and southeast. Most of the rocks that underlie the Edwards-Trinity aquifer are much less permeable than those that compose the aquifer and, thus, serve as a barrier to groundwater flow. Locally, however, the underlying rocks are permeable and are hydraulically connected to the Edwards-Trinity aquifer, thus extending the thickness of the flow system. The aquifer is generally recharged by direct precipitation on the land surface. Water is mostly unconfined in the shallow parts of the aquifer and is confined in the deeper zones.
Caves
Sources/Usage: Public Domain.Inside the Edwards-Trinity Plateau aquifer, Sonora Caverns, Sonora, Texas. (Credit: Eve Kuniansky, USGS.) Springs
Featured Studies and Datasets
Aquifer-scale studies and the datasets they produce are a key component to understanding how karst aquifers behave, and the quality of water within them.
- National Water-Quality Assessment, South-Central Texas — A program to describe the status and trends in water quality of a large, representative part of the Nation's surface-water and groundwater resources.
Additional Information
The following websites are additional sources of information about this aquifer:
- Texas Water Development Board: Springs Monitoring Program
- Edwards Aquifer Authority
- Barton Springs Edwards Aquifer Conservation District
- San Marcos Salamander Photos - U.S. Fish and Wildlife Service National Digital Library
- Barton Springs Salamander Photos - U.S. Fish and Wildlife Service National Digital Library
- Science
Below are other science projects associated with karst aquifers.
Karst Aquifers
Karst terrain is created from the dissolution of soluble rocks, principally limestone and dolomite. Karst areas are characterized by distinctive landforms (like springs, caves, sinkholes) and a unique hydrogeology that results in aquifers that are highly productive but extremely vulnerable to contamination.Filter Total Items: 13Karst Aquifers: Arbuckle-Simpson Aquifer
The Arbuckle-Simpson aquifer, which underlies more than 500 square miles in south central Oklahoma, is the principal water source for approximately 39,000 people in several cities in the region. The U.S. Environmental Protection Agency has designated the aquifer's eastern portion as a Sole Source Aquifer, a mechanism to protect drinking water supplies in areas with limited water supply.Karst Aquifers: Basin and Range and Bear River Range Carbonate Aquifers
In the Basin and Range, bedrock is present in the uplifted blocks of the mountain ranges and beneath fill in the valleys. While some of this bedrock is relatively impermeable, fracturing may enable groundwater to circulate through the rock, enlarging and increasing the size and number of pathways for water movement. This can ultimately produce a permeable water-yielding unit.Karst Aquifers: Colorado Plateau Karst
In northern and central Arizona, the Kaibab Limestone and its equivalents are karstic. North of the Grand Canyon, subterranean openings are primarily widely spaced fissures, while south of the Grand Canyon, fissures are more closely spaced and a few shallow caves are present.Karst Aquifers: Edwards Balcones Fault Zone Aquifer
The Edwards aquifer is the most transmissive of all the aquifers in Texas and Oklahoma, with large discharges from springs and from flowing and pumped wells. This aquifer demonstrates karst features such as springs and in-stream sinkholes, as well as endangered species.Karst Aquifers: Edwards-Trinity Plateau Aquifer
The Edwards-Trinity aquifer, located in the Trans-Pecos and the Edwards Plateau areas, is composed of relatively flat-lying rocks that are generally exposed at the land surface. This aquifer is generally recharged by precipitation; water is mostly unconfined in the shallow parts of the aquifer and is confined in the deeper zones.Karst Aquifers: Upper Floridan and Biscayne Aquifers
Covering approximately 100,000 square miles of the southeastern United States, the Floridan aquifer system (FAS) is one of the most productive aquifers in the world. The FAS is the primary source of drinking water for almost 10 million people, with nearly 50 percent of all water withdrawals being used for industrial purposes and agricultural irrigation.Karst Aquifers: Madison Aquifer
The Madison aquifer underlies eight states in the U.S. and Canada. It is an important water resource in the northern plains states where surface water supplies are limited and population is increasing. Declining water levels are a major issue for many of the communities that rely on this aquifer.Karst Aquifers: Midwest Paleozoic Carbonate Aquifers
The porosity of carbonate and dolomitic units in Midwest Paleozoic rocks has been enhanced by dissolution, and in many areas these rocks have undergone extensive karst development. This aquifer demonstrates karst features such as disappearing streams, springs, and caves.Karst Aquifers: New England Karst Aquifers
The New England Karst Aquifers feature crystalline limestones and marbles, narrow fissures, and some small caves.Karst Aquifers: Ozark Plateau Karst Aquifers
The Ozark Plateaus aquifer system consists of two aquifers, the Springfield Plateau aquifer and the Ozark aquifer, and an intervening confining unit. The system consists of mostly of carbonate rocks that are Cambrian through Mississippian in age.Karst Aquifers: Roswell Basin Aquifer
The Roswell Artesian Basin consists of an eastward-dipping carbonate aquifer overlain by a leaky evaporitic confining unit, overlain in turn by an unconfined alluvial aquifer. This aquifer provides habitat for several federally listed endangered invertebrate species. Decades of intensive pumping have caused substantial declines in hydraulic head in the aquifer.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. - Publications