Lake Texcoco
Overview
 
Lake Texcoco was a natural lake
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

 formation within the Valley of Mexico
Valley of Mexico
The Valley of Mexico is a highlands plateau in central Mexico roughly coterminous with the present-day Distrito Federal and the eastern half of the State of Mexico. Surrounded by mountains and volcanoes, the Valley of Mexico was a centre for several pre-Columbian civilizations, including...

. The Aztecs built the city of Tenochtitlan on an island in the lake. The Spaniards built Mexico City
Mexico City
Mexico City is the Federal District , capital of Mexico and seat of the federal powers of the Mexican Union. It is a federal entity within Mexico which is not part of any one of the 31 Mexican states but belongs to the federation as a whole...

 over Tenochtitlan. Efforts to control flooding led to most of the lake being drained, leaving a much smaller Lake Texcoco west of the city, surrounded by salt marsh.

The Valley of Mexico
Valley of Mexico
The Valley of Mexico is a highlands plateau in central Mexico roughly coterminous with the present-day Distrito Federal and the eastern half of the State of Mexico. Surrounded by mountains and volcanoes, the Valley of Mexico was a centre for several pre-Columbian civilizations, including...

 is a basin with an average elevation
Elevation
The elevation of a geographic location is its height above a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface ....

 of 2236 metres (7,336 ft) above mean sea level
Above mean sea level
The term above mean sea level refers to the elevation or altitude of any object, relative to the average sea level datum. AMSL is used extensively in radio by engineers to determine the coverage area a station will be able to reach...

 located in the southern highlands of Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

's central altiplano.
Encyclopedia
Lake Texcoco was a natural lake
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

 formation within the Valley of Mexico
Valley of Mexico
The Valley of Mexico is a highlands plateau in central Mexico roughly coterminous with the present-day Distrito Federal and the eastern half of the State of Mexico. Surrounded by mountains and volcanoes, the Valley of Mexico was a centre for several pre-Columbian civilizations, including...

. The Aztecs built the city of Tenochtitlan on an island in the lake. The Spaniards built Mexico City
Mexico City
Mexico City is the Federal District , capital of Mexico and seat of the federal powers of the Mexican Union. It is a federal entity within Mexico which is not part of any one of the 31 Mexican states but belongs to the federation as a whole...

 over Tenochtitlan. Efforts to control flooding led to most of the lake being drained, leaving a much smaller Lake Texcoco west of the city, surrounded by salt marsh.

The Valley of Mexico
Valley of Mexico
The Valley of Mexico is a highlands plateau in central Mexico roughly coterminous with the present-day Distrito Federal and the eastern half of the State of Mexico. Surrounded by mountains and volcanoes, the Valley of Mexico was a centre for several pre-Columbian civilizations, including...

 is a basin with an average elevation
Elevation
The elevation of a geographic location is its height above a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface ....

 of 2236 metres (7,336 ft) above mean sea level
Above mean sea level
The term above mean sea level refers to the elevation or altitude of any object, relative to the average sea level datum. AMSL is used extensively in radio by engineers to determine the coverage area a station will be able to reach...

 located in the southern highlands of Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...

's central altiplano. It formerly extended over a large portion in the southern half of the basin, where it was the largest of an interconnected chain of five major and several smaller lakes (the other main lakes being Xaltocan, Zumpango, Chalco
Lake Chalco
Lake Chalco was an endorheic lake formerly located in the Valley of Mexico and was important for human development in central Mexico. The lake was named after the city of Chalco on its eastern shore....

 and Xochimilco
Lake Xochimilco
Lake Xochimilco is an ancient endorheic lake located in the Valley of Mexico, part of a series of lakes, which included the brackish Lake Texcoco, Lake Zumpango, and Lake Xaltocan and the fresh water Lake Chalco...

 lakes). During periods of high water levels—typically after the May-to-October rainy seasons—the lakes were often joined as one body of water, at an average elevation
Elevation
The elevation of a geographic location is its height above a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface ....

 of 2242 metres (7,356 ft) above mean sea level
Above mean sea level
The term above mean sea level refers to the elevation or altitude of any object, relative to the average sea level datum. AMSL is used extensively in radio by engineers to determine the coverage area a station will be able to reach...

. In the drier winter months the lake system tended to separate into individual bodies of water, a flow that was mitigated by the construction of dikes and causeways in the Late Postclassic period of Mesoamerican chronology
Mesoamerican chronology
Mesoamerican chronology divides the history of pre-Columbian Mesoamerica into several periods: the Paleo-Indian , the Archaic , the Preclassic , the Classic , and the Postclassic...

. Lake Texcoco was the lowest-lying of all the lakes, and occupied the minimum elevation in the valley so that water ultimately drained towards it. The Valley of Mexico has been a closed basin since at least the Late Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

, and the lakes subsequently had no natural surface outflow
Discharge (hydrology)
In hydrology, discharge is the volume rate of water flow, including any suspended solids , dissolved chemical species and/or biologic material , which is transported through a given cross-sectional area...

, with the drainage basin
Drainage basin
A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 forming an endorheic system.

The lake basin is now occupied by Mexico City
Mexico City
Mexico City is the Federal District , capital of Mexico and seat of the federal powers of the Mexican Union. It is a federal entity within Mexico which is not part of any one of the 31 Mexican states but belongs to the federation as a whole...

, the capital of the present-day nation of Mexico.

History

In the Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....

 era, the lake occupied an even greater area. There were several paleo-lakes that would connect with each other from time to time. At the north in the modern community of San Miguel Tocuila there is a great paleontological field
Paleontological Museum in Tocuila
The Paleontological Museum in Tocuila displays part of one of the richest deposits of Late Pleistocene fauna in America...

, with a lot of pleistocenic fauna
Fauna
Fauna or faunæ is all of the animal life of any particular region or time. The corresponding term for plants is flora.Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g. the "Sonoran Desert fauna" or the "Burgess shale fauna"...

. The disarticulated remains of seven mammoth
Mammoth
A mammoth is any species of the extinct genus Mammuthus. These proboscideans are members of Elephantidae, the family of elephants and mammoths, and close relatives of modern elephants. They were often equipped with long curved tusks and, in northern species, a covering of long hair...

s dated between 10,220 ± 75 and 12,615 ± 95 years (BP
Before Present
Before Present years is a time scale used in archaeology, geology, and other scientific disciplines to specify when events in the past occurred. Because the "present" time changes, standard practice is to use AD 1950 as the origin of the age scale, reflecting the fact that radiocarbon...

) were found, suggesting human presence.

Agriculture around the lake began about 7,000 years ago, with humans following the patterns of periodic inundations of the lake.

On the northeast side of the lake, between 1700
17th century BC
The 17th century BC is a century which lasted from 1700 BC to 1601 BC.-Events:*c. 1700 BC: Indus Valley Civilization comes to an end but is continued by the Cemetery H culture*1700 BC: Belu-bani became the King of Assyria....

 and 1250 BCE
Common Era
Common Era ,abbreviated as CE, is an alternative designation for the calendar era originally introduced by Dionysius Exiguus in the 6th century, traditionally identified with Anno Domini .Dates before the year 1 CE are indicated by the usage of BCE, short for Before the Common Era Common Era...

, several villages appear. By 1250 BCE, the identifying signs of the Tlatilco culture
Tlatilco culture
Tlatilco culture is a culture that flourished in the Valley of Mexico between the years 1250 BCE and 800 BCE, during the Mesoamerican Early Formative period...

, including more complex settlements and a stratified social structure, are seen around the lake. By roughly 800 BCE, Cuicuilco
Cuicuilco
Cuicuilco is an important archaeological Mesoamerican Middle and Late Formative period site located on the southern shore of the Lake Texcoco in the southeastern Valley of Mexico. Today, it is a significant archaeological site that was occupied during the Early Formative until its destruction in...

 had eclipsed the Tlatilco cultural centers and was the major power in the Valley of Mexico during the next 200 years, when its famous conical pyramid
Pyramid
A pyramid is a structure whose outer surfaces are triangular and converge at a single point. The base of a pyramid can be trilateral, quadrilateral, or any polygon shape, meaning that a pyramid has at least three triangular surfaces...

 was built. The Xitle volcano destroyed Cuicuilco around 30 CE, a destruction that may have given rise to Teotihuacan
Teotihuacan
Teotihuacan – also written Teotihuacán, with a Spanish orthographic accent on the last syllable – is an enormous archaeological site in the Basin of Mexico, just 30 miles northeast of Mexico City, containing some of the largest pyramidal structures built in the pre-Columbian Americas...

.

After the fall of Teotihuacan, 600–800 CE, several other city states appeared around the lake, including Xoloc, Azcapotzalco
Azcapotzalco (altepetl)
Azcapotzalco was a pre-Columbian Nahua altepetl , capital of the Tepanec empire, in the Valley of Mexico, on the western shore of Lake Texcoco.The name Azcapotzalco means "at the anthill" in Nahuatl...

, Tlacopan
Tlacopan
Tlacopan , also called Tacuba, was a Pre-Columbian Mesoamerican city-state situated on the western shore of Lake Texcoco.Founded by Tlacomatzin, Tlacopan was a Tepanec kingdom subordinate to nearby Azcapotzalco...

, Coyohuacan, Culhuacán, Chimalpa and Chimalhuacán – mainly from Toltec
Toltec
The Toltec culture is an archaeological Mesoamerican culture that dominated a state centered in Tula, Hidalgo in the early post-classic period of Mesoamerican chronology...

 and Chichimeca
Chichimeca
Chichimeca was the name that the Nahua peoples of Mexico generically applied to a wide range of semi-nomadic peoples who inhabited the north of modern-day Mexico and southwestern United States, and carried the same sense as the European term "barbarian"...

 influence. None of these predominated and they coexisted more or less in peace for several centuries. This time was described as a Golden age in Aztec chronicles. By the year 1300, however, the Tepanec from Azcapotzalco were beginning to dominate the area. If Tenochtitlan was the capital city of the Aztec Empire, and Mexico City the capital of Mexico, then Lake Texcoco is the Lake of the capitals, and therefore very important to Mesoamerican history.

Tenochtitlan

According to a traditional story, the Mexica
Mexica
The Mexica were a pre-Columbian people of central Mexico.Mexica may also refer to:*Mexica , a board game designed by Wolfgang Kramer and Michael Kiesling*Mexica , a 2005 novel by Norman Spinrad...

 wandered in the deserts of modern Mexico for 100 years before they came to the thick forests of the place now called the Valley of Mexico.

Tenochtitlan was founded on an islet
Islet
An islet is a very small island.- Types :As suggested by its origin as islette, an Old French diminutive of "isle", use of the term implies small size, but little attention is given to drawing an upper limit on its applicability....

 in the western part of the lake in the year 1325. Around it, the Aztec
Aztec
The Aztec people were certain ethnic groups of central Mexico, particularly those groups who spoke the Nahuatl language and who dominated large parts of Mesoamerica in the 14th, 15th and 16th centuries, a period referred to as the late post-classic period in Mesoamerican chronology.Aztec is the...

s created a large artificial island
Artificial island
An artificial island or man-made island is an island or archipelago that has been constructed by people rather than formed by natural means...

 using a system similar to the creation of chinampa
Chinampa
Chinampa is a method of ancient Mesoamerican agriculture which used small, rectangle-shaped areas of fertile arable land to grow crops on the shallow lake beds in the Valley of Mexico.-Description:...

s. To overcome the problems of drinking water, the Aztecs built a system of dam
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...

s to separate the salty waters of the lake from the rain water of the effluent
Effluent
Effluent is an outflowing of water or gas from a natural body of water, or from a human-made structure.Effluent is defined by the United States Environmental Protection Agency as “wastewater - treated or untreated - that flows out of a treatment plant, sewer, or industrial outfall. Generally refers...

s. It also permitted them to control the level of the lake. The city also had an inner system of channels that helped to control the water.

During Cortés's
Hernán Cortés
Hernán Cortés de Monroy y Pizarro, 1st Marquis of the Valley of Oaxaca was a Spanish Conquistador who led an expedition that caused the fall of the Aztec Empire and brought large portions of mainland Mexico under the rule of the King of Castile in the early 16th century...

 siege of Tenochtitlan, the dams were destroyed, and never rebuilt, so flood
Flood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...

ing became a big problem for the new Mexico City
Mexico City
Mexico City is the Federal District , capital of Mexico and seat of the federal powers of the Mexican Union. It is a federal entity within Mexico which is not part of any one of the 31 Mexican states but belongs to the federation as a whole...

 built over Tenochtitlan.

Artificial drainage

Mexico City suffered from periodic floods; in 1604 the lake flooded the city with an even more severe flood following in 1607. Under the direction of Enrico Martínez
Enrico Martínez
Enrico Martínez , Henri Martín or Heinrich Martin, was cosmographer to the King of Spain, interpreter for the Spanish Inquisition, publisher, and hydraulic engineer....

 a drain was built to control the level of the lake, but in 1629 another flood kept most of the city covered for five years. In that time it was debated whether to relocate the city, but the Spanish
Spain
Spain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...

 authorities decided to keep the current location.

Eventually the lake was drained, by the channels and a tunnel to the Pánuco River
Pánuco River
The Pánuco River is a river in Mexico that flows from the River Moctezuma in the Valley of Mexico to the Gulf of Mexico.At its source, it serves as a channel for water-drainage for Mexico City. From there, it becomes the state border between Hidalgo and Querétaro as it moves towards San Luis...

, but even that could not stop floods, since by then most of the city was under the phreatic
Phreatic
The term phreatic is used in Earth sciences to refer to matters relating to ground water below the water table . The term 'phreatic surface' indicates the location where the pore water pressure is under atmospheric conditions...

 level. The flooding could not be completely controlled until the twentieth century. In 1967 construction of the Drenaje Profundo ("Deep Drainage
Drainage
Drainage is the natural or artificial removal of surface and sub-surface water from an area. Many agricultural soils need drainage to improve production or to manage water supplies.-Early history:...

 System"), a network of several hundred kilometers of tunnels, at a depth between 30 and 250 m (98.4 and 820.2 ft). The central tunnel has a diameter of 6.5 metres (21.3 ft) and carries rain water out of the basin.

The ecological consequences of the draining were enormous. Parts of the valleys were turned semi-arid, and even today Mexico City suffers for lack of water. Current pumping of water from underground is one of the reasons Mexico City is sinking at a rate of a few centimeters every year.

The term "Texcoco Lake" now refers only to a small area surrounded by salt marsh
Salt marsh
A salt marsh is an environment in the upper coastal intertidal zone between land and salt water or brackish water, it is dominated by dense stands of halophytic plants such as herbs, grasses, or low shrubs. These plants are terrestrial in origin and are essential to the stability of the salt marsh...

es 4 kilometres (2.5 mi) east of Mexico City, which covers the ancient lake bed. Also there are small remnants of the lakes of Xochimilco
Xochimilco
Xochimilco is one of the sixteen delegaciones or boroughs within Mexican Federal District. The borough is centered on the formerly independent city of Xochimilco, which was established on what was the southern shore of Lake Xochimilco in the pre-Hispanic period...

, Chalco
Chalco
Aluminum Corporation of China Limited, also known as Chalco , is a multinational aluminum company headquartered in Beijing, People's Republic of China...

, and Zumpango.

Several species indigenous to the lake are now extinct or endangered (e.g. axolotl
Axolotl
The axolotl , Ambystoma mexicanum, is a neotenic salamander, closely related to the Tiger Salamander. Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled. It is also called ajolote...

s).

The modern Texcoco Lake has a high concentration of salts, and its waters are evaporated for their processing. A Mexican company, "Sosa Texcoco S.A" has an 800 hectares (1,976.8 acre) solar evaporator known as "El caracol".

External links

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