The Ogallala aquifer underlies portions of eight states. This image documents the decline in the level of water in many areas for the period 1980-1995. Source: USGS

The Ogallala Aquifer, also known as the High Plains Aquifer, is a vast yet shallow underground water table aquifer located beneath the Great Plains in the United States. One of the world's largest aquifers, it lies under about 174,000 mi² (450,000 km²) in portions of the eight states of South Dakota, Nebraska, Wyoming, Colorado, Kansas, Oklahoma, New Mexico, and Texas. It was named in 1899 by N.H. Darton from its type locality near the town of Ogallala, Nebraska. Image File history File links Download high resolution version (492x720, 64 KB) Please see the file description page for further information. ... Image File history File links Download high resolution version (492x720, 64 KB) Please see the file description page for further information. ... Cross section showing the water table varying with surface topography as well as a perched water table The water table or phreatic surface is the surface where the water pressure is equal to atmospheric pressure. ... An aquifer is an underground layer of water-bearing permeable rock or unconsolidated materials (gravel, sand, silt, or clay) from which groundwater can be usefully extracted using a water well. ... The Great Plains covers much of the central United States, portions of Canada and Mexico. ... Federal courts Supreme Court Chief Justice Associate Justices Elections Presidential elections Midterm elections Political Parties Democratic Republican Third parties State & Local government Governors Legislatures (List) State Courts Counties/Parishes/Boroughs, Cities, and Towns Other countries Politics Portal      A U.S. state is any one of the fifty subnational entities of... Official language(s) English Capital Pierre Largest city Sioux Falls Area  Ranked 17th  - Total 77,163 sq mi (199,905 km²)  - Width 210 miles (340 km)  - Length 380 miles (610 km)  - % water 1. ... Official language(s) English Capital Lincoln Largest city Omaha Largest metro area Omaha Area  Ranked 16th  - Total 77,421 sq mi (200,520 km²)  - Width 210 miles (340 km)  - Length 430 miles (690 km)  - % water 0. ... Official language(s) English Capital Cheyenne Largest city Cheyenne Area  Ranked 10th  - Total 97,818 sq mi (253,348 km²)  - Width 280 miles (450 km)  - Length 360 miles (580 km)  - % water 0. ... Official language(s) English Capital Denver Largest city Denver Area  Ranked 8th  - Total 104,185 sq mi (269,837 km²)  - Width 280 miles (451 km)  - Length 380 miles (612 km)  - % water 0. ... Official language(s) none Capital Topeka,Kandickass Topeka Largest city Wichita Area  Ranked 15th  - Total 82,277 sq mi (213,096 km²)  - Width 211 miles (340 km)  - Length 417 miles (645 km)  - % water 0. ... Official language(s) None Capital Oklahoma City Largest city Oklahoma City Area  Ranked 20th  - Total 69,960 sq mi (181,196 km²)  - Width 230 miles (370 km)  - Length 298 miles (480 km)  - % water 1. ... Capital Santa Fe Largest city Albuquerque Area  Ranked 5th  - Total 121,665 sq mi (315,194 km²)  - Width 342 miles (550 km)  - Length 370 miles (595 km)  - % water 0. ... Official language(s) No Official Language See languages of Texas Capital Austin Largest city Houston Area  Ranked 2nd  - Total 261,797 sq mi (678,051 km²)  - Width 773 miles (1,244 km)  - Length 790 miles (1,270 km)  - % water 2. ... Year 1899 (MDCCCXCIX) was a common year starting on Sunday (link will display the full calendar). ... Darton in about 1895 Nelson Horatio Darton (1865-1948) was a geologist who worked for the United States Geological Survey. ... In some natural sciences, type locality (Latin locus typicus) is the typical or representative location and is typically the first example of a newly discovered or described object. ... Sign for Front Street a popular Old West-themed tourist attraction in Ogallala Ogallala is a city located in Keith County, Nebraska. ...

General characteristics

The deposition of the aquifer material dates back 2 to 6 million years to late Miocene to early Pliocene age when the southern Rocky Mountains were still tectonically somewhat active. From the uplands to the west, rivers and streams cut channels in a generally west to east or southeast direction. Erosion of the Rockies provided alluvial and eolian sediment that filled the ancient channels and eventually covered the entire area of the present-day aquifer, forming the water-bearing Ogallala Formation. The depth of the formation varies with the shape of the pre-Ogallala surface, being deepest where it fills ancient valleys and channels. The Ogallala Formation consists mostly of coarse sedimentary rocks in its lower sections, which grade upward into finer-grained lithologies.^[1] The Miocene Epoch is a period of time that extends from about 23. ... The Pliocene epoch (spelled Pleiocene in some older texts) is the period in the geologic timescale that extends from 5. ... The Rocky Mountains, often called the Rockies, are a broad mountain range in western North America. ... Severe soil erosion in a wheat field near Washington State University, USA. For erosion as an operation of Mathematical morphology, see Erosion (morphology) Erosion is displacement of solids (soil, mud, rock and other particles) by the agents of ocean currents, wind, water, or ice by downward or down-slope movement... Alluvium is soil land deposited by a river or other running water. ... Eolian (or aeolian) processes pertain to the activity of the winds. ... Petrology is a field of geology which focuses on the study of rocks and the conditions by which they form. ...

The water-permeated thickness of the Ogallala Formation ranges from a few feet to more than 1000 feet (300 m) and is generally greater in the northern plains.^[2] The depth of the water below the surface of the land ranges from almost 400 feet (122 m) in parts of the north to between 100 to 200 feet (30 to 61 m) throughout much of the North. Present-day recharge of the aquifer with fresh water occurs at a slow rate; this implies that much of the water in its pore spaces is paleowater, dating back to the last ice age. Porosity is a measure of the void spaces in a material, and is measured as a fraction, between 0–1, or as a percent between 0–100%. The term porosity is used in multiple fields including manufacturing, earth sciences and construction. ... Fossil water or paleowater is groundwater that has remained in an aquifer for thousands or more years. ... Variations in CO2, temperature and dust from the Vostok ice core over the last 400 000 years For the animated movie, see Ice Age (movie). ...

Aquifer water balance

An aquifer is a groundwater storage reservoir in the water cycle. While groundwater is a renewable source, reserves replenish relatively slowly. The USGS has performed several studies of the aquifer, to determine what is coming in (groundwater recharge from the surface), what is leaving (pumping and baseflow to streams) and what the net changes in storage are (rise, fall or no change — see figure above). Simply put, water in, less the water out, is equal to the change in water stored in the aquifer. This type of mass-balance "accounting" is how hydrologic budgets are performed, and is a crucial first step in sustainable management of any natural resource. Presently, groundwater in the United States is utilized approximately four times faster than it is naturally replaced.^{[citation needed]} The movement of water around, over, and through the Earth is called the water cycle. ... The United States Geological Survey (USGS) is a scientific agency of the United States government. ... The law of conservation of mass/matter, also known as law of mass/matter conservation (or the Lomonosov-Lavoisier law), states that the mass of a closed system of substances will remain constant, regardless of the processes acting inside the system. ...

Groundwater recharge

The rate at which recharge water enters the aquifer is limited by several factors. Much of the plains region is semi-arid with steady winds that hasten evaporation of surface water and precipitation. In many locations, the aquifer is overlain, in the vadose zone, with a shallow layer of caliche that is practically impermeable; this limits the amount of water able to recharge the aquifer from the land surface. However, the soil of the playa lakes is different and not lined with caliche, making these some of the few areas where the aquifer can recharge. The destruction of playas by farmers and development then decreases the available recharge area. The prevalence of the caliche is partly due to the ready evaporation of soil moisture and the semi-arid climate; the aridity increases the amount of evaporation which increases the amount of caliche in the soil. Both mechanisms reinforce the difficulty recharge has in reaching the water table. A steppe in Western Kazakhstan in early spring In physical geography, a steppe (Russian: - , Ukrainian: - , Kazakh: - ), pronounced in English as , is a plain without trees (apart from those near rivers and lakes); it is similar to a prairie, although a prairie is generally considered as being dominated by tall grasses... The vadose zone, also termed the unsaturated zone, is the portion of Earth between the land surface and the water table, and is thus not considered groundwater (vadose is Latin for shallow). It comprises the unsaturated portion of the soil, regolith or bedrock, as well as the saturated capillary fringe... Caliche is a hardened deposit of calcium carbonate. ... written by AmerHydraulic conductivity, mathematically represented as , is a property of soil or rock, in the vadose zone or groundwater, that describes the ease with which water can move through pore spaces or fractures. ... It has been suggested that this article or section be merged into Playa. ...

Groundwater discharge

NASA ASTER image of an approx. 557 mi² area of fields (1443 km²) in Kansas which are watered from the Ogallala aquifer with center pivot irrigation systems.

The regions overlying the Ogallala aquifer are some of the most productive regions for ranching livestock, and growing corn, wheat and soybeans in the United States (often called the "breadbasket of America"). The success of large-scale farming in areas which do not have adequate precipitation and do not always have perennial surface water for diversion depends heavily on pumping groundwater for irrigation. Image File history File links Download high resolution version (2589x2481, 1365 KB) Summary Licensing File links The following pages link to this file: Agriculture Crop rotation Center pivot irrigation Haskell County, Kansas Ogallala Aquifer Agriculture in the United States Wikipedia:Featured picture candidates Wikipedia:Featured picture candidates/Image:Crops Kansas... Image File history File links Download high resolution version (2589x2481, 1365 KB) Summary Licensing File links The following pages link to this file: Agriculture Crop rotation Center pivot irrigation Haskell County, Kansas Ogallala Aquifer Agriculture in the United States Wikipedia:Featured picture candidates Wikipedia:Featured picture candidates/Image:Crops Kansas... ASTER image ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) is one of five remote sensory devices on board the Terra satellite launched into Earth orbit by NASA in 1999. ... Official language(s) none Capital Topeka,Kandickass Topeka Largest city Wichita Area  Ranked 15th  - Total 82,277 sq mi (213,096 km²)  - Width 211 miles (340 km)  - Length 417 miles (645 km)  - % water 0. ... Sahara Irrigation (in agriculture) is the replacement or supplementation of rainfall with water from another source in order to grow crops. ... Sheep are commonly bred as livestock. ... “Corn” redirects here. ... Species T. aestivum T. boeoticum T. compactum T. dicoccoides T. dicoccon T. durum T. monococcum T. spelta T. sphaerococcum T. timopheevii References:   ITIS 42236 2002-09-22 For the indie rock group see: Wheat (band). ... Binomial name Glycine max Soybeans (US) or soya beans (UK) (Glycine max) are a high-protein legume (Family Fabaceae) grown as food for both humans and livestock. ...

Early settlers of the semi-arid High Plains were plagued by crop failures due to cycles of drought, culminating in the disastrous Dust Bowl of the 1930s. The aquifer was first tapped for irrigation in 1911. Large scale use for irrigation began in the 1930s and continued through the 1950s, due to the availability of electric power to rural farming communities and the development of cheap and efficient electric turbine pumps. It was only after World War II that affordable technology became available to substantially extract water. This transformed the High Plains into one of the most agriculturally productive regions in the world. During the early years, this source of water was thought to be inexhaustible, and its hydrology a mystery. However, because the rate of extraction exceeds the rate of recharge, water level elevations are decreasing. At some places the water table was measured to drop more than five feet (1.5 m) per year at the time of maximum extraction. In extreme cases, the deepening of wells was required to reach the steadily falling water table; and it has even been drained (dewatered) in some places such as Northern Texas. Today, water is being extracted at rates exceeding one hundred times the natural replacement rate.^{[citation needed]} Utilizing treated recycled sources of water in agriculture is one approach at vouchsafing the future of what may justifiably be considered a national treasure. Another method to reducing the amount of water use is changing to a crop that requires less water, such as sunflowers.^[3] This article does not adequately cite its references. ... Irrigation is the artificial application of water to the soil. ... Face The 1930s (years from 1930–1939) were described as an abrupt shift to more radical and conservative lifestyles, as countries were struggling to find a solution to the Great Depression, also known in Europe as the World Depression. ... This does not cite any references or sources. ... An electrically driven pump (electropump) for waterworks near the Hengsteysee, Germany. ... Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000... Cable tool water well drilling rig in Kimball, West Virginia. ... Binomial name Helianthus annuus L. The sunflower (Helianthus annuus) is an annual plant native to the Americas in the family Asteraceae, with a large flowering head (inflorescence). ...

Several of the rivers in the region, such as the Platte, in places are below the water level of the aquifer and therefore the rivers actually receive groundwater flow (baseflow) rather than supply recharge to the aquifer. The Platte River, showing the North Platte and South Platte The Platte River is a tributary of the Missouri River, approximately 310 mi. ...

Change in groundwater storage

Water conservation practices (terracing and crop rotation), more efficient irrigation methods (center pivot and drip), and simply reduced area under irrigation have helped to slow depletion of the aquifer, but levels are generally still dropping, particularly in the southern parts at rates exceeding one hundred times the replacement rate.^{[citation needed]} See the figure above for an illustration of the places where large drops in water level have been observed (i.e., the red areas in Texas and southern Kansas). In the more humid areas water levels have actually risen since 1980 (i.e., eastern and central Nebraska and south of Lubbock). Agricultural dependence on this valuable water source needs to change within a generation in order to save this invaluable groundwater source. Terraced vineyards near Lausanne The Incan terraces at Písac are still used today. ... Sahara Irrigation (in agriculture) is the replacement or supplementation of rainfall with water from another source in order to grow crops. ... Official language(s) No Official Language See languages of Texas Capital Austin Largest city Houston Area  Ranked 2nd  - Total 261,797 sq mi (678,051 km²)  - Width 773 miles (1,244 km)  - Length 790 miles (1,270 km)  - % water 2. ... Official language(s) none Capital Topeka,Kandickass Topeka Largest city Wichita Area  Ranked 15th  - Total 82,277 sq mi (213,096 km²)  - Width 211 miles (340 km)  - Length 417 miles (645 km)  - % water 0. ... Official language(s) English Capital Lincoln Largest city Omaha Largest metro area Omaha Area  Ranked 16th  - Total 77,421 sq mi (200,520 km²)  - Width 210 miles (340 km)  - Length 430 miles (690 km)  - % water 0. ... Nickname: Hub City Location within the state of Texas Coordinates: County Lubbock County Government  - Mayor David Miller Area  - City 297. ...

Other mentions of Ogallala aquifer

The importance of this aquifier has been recognized recently in many works, ranging from increased attention from journalism^[4][5][6] to a mention in a plot for world domination in the Amazing Spider-man comic book made by Marvel Comics.^[7] Increased oversight and regulation of the aquifer by the federal government does not appear to be forthcoming, though the economic and environmental implications of the potential decline of the region are significant. Spider-Man swinging around his hometown, New York City. ...

See also

• Hydrogeology
• Aquifer and Water table
• Groundwater*

Hydrogeology (hydro- meaning water, and -geology meaning the study of the Earth) is the part of hydrology that deals with the distribution and movement of groundwater in the soil and rocks of the Earths crust, (commonly in aquifers). ... An aquifer is an underground layer of water-bearing permeable rock or unconsolidated materials (gravel, sand, silt, or clay) from which groundwater can be usefully extracted using a water well. ... Cross section showing the water table varying with surface topography as well as a perched water table The water table or phreatic surface is the surface where the water pressure is equal to atmospheric pressure. ... Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of geologic formations. ...

References

April 9 is the 99th day of the year in the Gregorian calendar (100th in leap years). ... 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the CE era. ...

External links

• USGS High Plains Regional Groundwater Study
• A Legal Fight in Texas over the Ogallala Aquifier
• Kansas Geological Survey information on the High Plains / Ogallala Aquifer

Coordinates: 36°59′26″N, 101°26′52″W Map of Earth showing lines of latitude (horizontally) and longitude (vertically), Eckert VI projection; large version (pdf, 1. ...