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.
What is Karst?
Karst aquifers are a vital groundwater resource in the United States. In the United States, about 40% of the groundwater used for drinking comes from karst aquifers.
Some karst areas in the United States are famous, such as the springs of Florida, Carlsbad Caverns in New Mexico, and Mammoth Cave in Kentucky, but in fact about 20 percent of the land surface in the U.S. is classified as karst. Other parts of the world with large areas of karst include China, Europe, the Caribbean, and Australia.
Karst hydrogeology is typified by a network of interconnected fissures, fractures and conduits emplaced in a relatively low-permeability rock matrix. Most of the groundwater flow and transport occurs through the network of openings, while most of the groundwater storage occurs in the matrix. As a result, most karst aquifers are highly heterogeneous and anisotropic, and much of karst research has focused on developing innovative approaches for better understanding and managing these valuable water resources.
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Principal Karst Aquifers
- Arbuckle-Simpson aquifer (OK) — Underlies more than 500 square miles in south central Oklahoma and is the principal water source for about 40,000 people. Many springs and small karst features, but only a few air-filled caves.
- Basin and Range and Bear River range carbonate aquifers (NV, UT) — Some fractured carbonate rocks beneath alluvial basin fill. Includes areas near Cedar Break Nat. Monument, Great Basin Nat. Park, and the Bear River Range.
- Colorado Plateau karst (AZ)
- Edwards Balcones Fault Zone aquifer (OK, TX) — Highly faulted and fractured carbonate rocks of Cretaceous age in an area of about 4,000 square miles in south-central Texas. Primary drinking-water supply for San Antonio, TX.
- Edwards-Trinity Plateau aquifer (AR, OK, TX) — Consists of rocks of Cretaceous age that are present in an area of about 35,500 square miles in west-central Texas.
- Upper Floridan and Biscayne aquifers (AL, GA, FL, MI, SC)
- Madison aquifer (MT, ND, NE, SD, WY, and Canada)— An important water resource in the northern plains states, where surface-water supplies are limited and population is increasing. It is one of the largest confined aquifer systems in the U.S.
- Midwest Paleozoic Carbonate aquifers (IA, IL, IN, MI, MN, OH, WI) — Karst developed in several Paleozoic aquifers that span the Midwest from Michigan to Tennessee. Contains some of the longest mapped caves in the world, including Kentucky's Mammoth Cave Nat. Park.
- New England karst aquifers (MA, ME, VT) — Solution terrain in crystalline limestones and marbles mainly in northeastern Maine, western Vermont, and western Massachusetts.
- Ozark Plateau karst aquifers (AR, KS, MO, OK) — Paleozoic carbonate rocks underlying several mid-continent states. Comprises two aquifers (Springfield and Ozark) and an intervening confining unit, and yields modest amounts of water.
- Roswell Basin aquifer (NM) — An eastward-dipping carbonate aquifer overlain by a leaky evaporitic confining unit and an unconfined alluvial aquifer. Decades of intensive pumping have caused substantial declines in hydraulic head.
- Pacific Northwest basalt aquifers (CA, ID, OR, WA) — Late Cenozoic basalt lava fields that contain lava tubes, fissures, open sinkholes, and caves formed by extrusion of the still-liquid portion of the lava.
- Valley and Ridge, Piedmont, and Blue Ridge aquifers (AL, GA, MD, NC, PA, SC, TN, WV, VA) — Extensive areas of karst within complex geologic structures, resulting in highly variable karst-aquifer characteristics. Includes the Great Valley aquifer, an important water resource for many cities.
Karst Interest Group and Workshop
The USGS Karst Interest Group’s (KIG) mission is to encourage and support interdisciplinary collaboration and technology transfer among scientists working in karst areas. The 8th USGS KIG Workshop will be held virtually on October 19-21, 2021. See the Karst Interest Group Workshop webpage for more information, and for proceedings from previous meetings.
Below are other science projects associated with karst 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 was October 22-24, 2024 in Nashville, TN.
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Karst 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.
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.
What is Karst?
Karst aquifers are a vital groundwater resource in the United States. In the United States, about 40% of the groundwater used for drinking comes from karst aquifers.
Some karst areas in the United States are famous, such as the springs of Florida, Carlsbad Caverns in New Mexico, and Mammoth Cave in Kentucky, but in fact about 20 percent of the land surface in the U.S. is classified as karst. Other parts of the world with large areas of karst include China, Europe, the Caribbean, and Australia.
Karst hydrogeology is typified by a network of interconnected fissures, fractures and conduits emplaced in a relatively low-permeability rock matrix. Most of the groundwater flow and transport occurs through the network of openings, while most of the groundwater storage occurs in the matrix. As a result, most karst aquifers are highly heterogeneous and anisotropic, and much of karst research has focused on developing innovative approaches for better understanding and managing these valuable water resources.
Media
Sources/Usage: Public Domain. View Media Details
Principal Karst Aquifers
- Arbuckle-Simpson aquifer (OK) — Underlies more than 500 square miles in south central Oklahoma and is the principal water source for about 40,000 people. Many springs and small karst features, but only a few air-filled caves.
- Basin and Range and Bear River range carbonate aquifers (NV, UT) — Some fractured carbonate rocks beneath alluvial basin fill. Includes areas near Cedar Break Nat. Monument, Great Basin Nat. Park, and the Bear River Range.
- Colorado Plateau karst (AZ)
- Edwards Balcones Fault Zone aquifer (OK, TX) — Highly faulted and fractured carbonate rocks of Cretaceous age in an area of about 4,000 square miles in south-central Texas. Primary drinking-water supply for San Antonio, TX.
- Edwards-Trinity Plateau aquifer (AR, OK, TX) — Consists of rocks of Cretaceous age that are present in an area of about 35,500 square miles in west-central Texas.
- Upper Floridan and Biscayne aquifers (AL, GA, FL, MI, SC)
- Madison aquifer (MT, ND, NE, SD, WY, and Canada)— An important water resource in the northern plains states, where surface-water supplies are limited and population is increasing. It is one of the largest confined aquifer systems in the U.S.
- Midwest Paleozoic Carbonate aquifers (IA, IL, IN, MI, MN, OH, WI) — Karst developed in several Paleozoic aquifers that span the Midwest from Michigan to Tennessee. Contains some of the longest mapped caves in the world, including Kentucky's Mammoth Cave Nat. Park.
- New England karst aquifers (MA, ME, VT) — Solution terrain in crystalline limestones and marbles mainly in northeastern Maine, western Vermont, and western Massachusetts.
- Ozark Plateau karst aquifers (AR, KS, MO, OK) — Paleozoic carbonate rocks underlying several mid-continent states. Comprises two aquifers (Springfield and Ozark) and an intervening confining unit, and yields modest amounts of water.
- Roswell Basin aquifer (NM) — An eastward-dipping carbonate aquifer overlain by a leaky evaporitic confining unit and an unconfined alluvial aquifer. Decades of intensive pumping have caused substantial declines in hydraulic head.
- Pacific Northwest basalt aquifers (CA, ID, OR, WA) — Late Cenozoic basalt lava fields that contain lava tubes, fissures, open sinkholes, and caves formed by extrusion of the still-liquid portion of the lava.
- Valley and Ridge, Piedmont, and Blue Ridge aquifers (AL, GA, MD, NC, PA, SC, TN, WV, VA) — Extensive areas of karst within complex geologic structures, resulting in highly variable karst-aquifer characteristics. Includes the Great Valley aquifer, an important water resource for many cities.
Karst Interest Group and Workshop
The USGS Karst Interest Group’s (KIG) mission is to encourage and support interdisciplinary collaboration and technology transfer among scientists working in karst areas. The 8th USGS KIG Workshop will be held virtually on October 19-21, 2021. See the Karst Interest Group Workshop webpage for more information, and for proceedings from previous meetings.
Below are other science projects associated with karst 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 was October 22-24, 2024 in Nashville, TN.
Filter Total Items: 13
Karst 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.