Colhué Huapi is an intermittent lake located in the central Patagonian region of the Argentine Republic, south of the province of Chubut, and together with Lake Musters forms the terminal phase of the current endorheic basin of the Senguerr River. Both lakes are located in the .
In March 2017 the lake was almost completely dry, mainly due to the artificial diversion of water from the Senguerr River and, to a lesser extent, to the drought that has been raging since 2000. It lies at an altitude of 310 m a.s.l. and the greatest width is 35 to 40 km from northwest to southeast.
Despite its large surface area when full, the lake is considered by many to be a giant lagoon because of its shallow depth. In the last 30 years the lake and the whole area around it have been experiencing a period of severe drought. This is a product of evaporation due to natural causes and undoubtedly human action was a factor that contributed to the watercourse disappearing faster. As the lake suffers the absence of liquid due to the great droughts, it leaves its bottom uncovered; then the winds form dunes that further erode the environment. As a major consequence this wind lashes the entire surrounding rural area and distant points such as the on the Argentine Sea.
The lake remains dry most of the year, with the exception of the few wetter months, which together with improvements in water abstraction policies means that the Falso Senguer drains part of its flow into the lake. This causes the fields near the lake to see a small lake intermittently until the summer season.
Toponymy
The name of this great water mirror comes from the Mapuche language (Mapudungun). The word Colhué means "red or reddish place". On the other hand, Huapi refers to "island". Thus, it can be assumed that the ancient inhabitants of the region called this lake this way in allusion to one of its rocky islands, or because of the clay colour of the water. It may also be a Mapuche expression meaning lake of the brown island. The same name was given to a nearby oil field and to an old Comodoro Rivadavia Railway near the lake, which served the homonymous spot.
Geography The lake used to be an orchard in the middle of the deserted Patagonian Steppe. The San Bernardo mountain range separates it from the neighbouring Lake Musters and the entire area around it is riddled with hills of low and high altitudes. The landscapes surrounding the lake are also accompanied by ancient extinct volcanoes.
The lake is criss-crossed by several peninsulas and headlands. However, the most prominent is the Grande or Namuncurá peninsula. This peninsula divides the northern part of Colhué Huapi in two. It runs in a straight line from north to south for about 20 kilometres and rises 500 metres above sea level at its highest point and is the most prominent coastal feature in sight from all sides. In terms of size, the Grande peninsula, seen from a distance from the lake shores, appears to be very high and rocky at the top. However, it consists of a superposition of sand and clay hills no more than 300 metres high in relation to the lake. At its southern end it decreases in height until it culminates in coarse sandy beaches, on which there is a scattering of medium-sized rocks, polished by the earthy wind.
Other highlights on the shores of the lake are the Chica peninsula and the Mocha peninsula with its high stone cliffs.
The lake used to have many islands, now reduced to sandy, wind-worn hills and two large, flat-roofed cliff islands. Today some of them still have vegetation.
The extensive drought has now caused the ruin of all the surrounding estancias, as well as the accumulation of extensive sand dunes that are spread over large distances for kilometres. The size of the sand dunes resulted in the creation of a Sahara-like desert with mounds of sand similar in size and shape to pyramids. The dunes have sand that was at the bottom of the lake as sediment and are moved with every wind, burying everything in their path.
Palaeontology Both the river and lake areas are important dinosaur sites with dinosaur specimens found and dinosaur egg remains. The area includes Cretaceous rocks, about 70 million years old, and a large number of hadrosaur remains.
History Ten thousand years ago, the Colhué Huapi and the neighbouring lake Musters formed a single lake. As a result, today's Mocha and Chica peninsulas were large islands. The ancient body of water was called Paleolake Sarmiento and its elevation reached over 326 m.a.s.l. (60 metres above the present level of Lake Musters). Subsequently, it declined and it is estimated that before 1600 BC the lakes were still connected and the bottom of the lower Sarmiento was almost entirely occupied by water. By 1500 BC the lakes would have reached a level similar to the present day and separated.
It is believed that the arid conditions that persist today, with certain variables, have been maintained from the last 5,000 - 6,000 years to the present.
The lake area was inhabited by aborigines throughout time. Because of this continuous presence, there are material records of hunter-gatherer peoples. Their presence was recorded in chenques (tombs), rock art and elements of their daily life. The lake enjoyed human preference over neighbouring Lake Musters, as evidenced by the large number and variety of archaeological features and indigenous burial sites that have been found there for decades. Recent studies have verified that hunter-gatherer groups practised intensive and continuous fishing since 1500 years ago.
It was the Tehuelches who gathered the oldest accounts of the lake. They claimed that its waters were inhabited by a monster known as lemisch (Yemis-che). The translation is water tiger. For the Indians it was a supernatural being of which they were superstitiously terrified, because of its ferocious appearance, its nocturnal habits, its strength and bellowing, and its complete invulnerability to remington shots. Carlos Ameghino, who was travelling through Chubut and Patagonia in search of fossil bones for his brother Florentino, mentioned to the latter in a letter that he had obtained from the Tehuelche Indians, some precious data about the famous lemisch. The scientist affirmed its veracity since he had seen in the possession of an Indian, a piece of lemisch leather, in which the small bones are embedded. These were sent to Florentino Ameghino and were found to resemble fossilised pieces of Mylodon remains. Until the 20th century, before the great droughts that left the lake empty, tales of the monster were still heard.
The lake was explored by the in 1886.
Western civilisation occupied the margins of the lake in the late 19th and early 20th centuries. Thus, the colonists settled where other past civilisations had previously developed. The children of the peoples of the past, still present at that time, within a few decades were incorporated into the western way of life. The old way of life became extinct within a few years.
In a report written by the German explorer Wilhelm Vallentin, during his tour of the region in 1904 and 1905. He described it as a lake about 50 kilometres long and just over 20 kilometres wide. It had been completely dry in former times.
In an essay on Sarmiento's colony in the 1968 Cuadernos de Historia del Chubut he states:"This lake presented an unknown, because of which it was always surrounded by mystery. What happened to its waters? Did they infiltrate? [...] as soon as the flows of the Senguer diminished, in Lake Colhué Huapi its great downpours began again, leaving enormous sandbanks uncovered".In 1914, the was established only 20 km from the lake. It promoted an agricultural settlement that used the waters of the river that feeds the lake. With the closure of the Comodoro Rivadavia to Colonia Sarmiento Railway in 1977, the village declined rapidly. However, even today it is still a place with agricultural production.
At the end of the first half of the 20th century, the lake was already suffering from recurrent low water levels. However, it never dried up completely. When the lake recovered, it grew to such an extent that in parts it covered the old route to Sarmiento. To combat the frequent floods, the inhabitants of the farms dug wells close to the shore.
Even in the 1950s, the river that carried its waters to the Chubut River was still flowing and had its last activity. Moreover, by that time the whole area adjacent to the lake had abundant water, farms, fruit trees, trees, plantations, it was a very green place, a place with a lot of vegetation. The 1950s are fundamental for the comparisons of the different levels of the lake over time. The Topographic charts from the 1950s and satellite photos from the early 2000s reveal the change in elevation and the successive recession of the lake. In those years, the Mocha peninsula was connected to the mainland by a narrow strip of land. Then, as the water receded, the plain became a lagoon linked to the lake by a channel, before finally becoming an independent lagoon that eventually mutated into the parched plain that we walk across.
By the 1960s the area adjacent to the lake had a large amount of sheep production with productive fields. The production was such that the estancia was able to produce cheese for sale in the now extinct , a former railway station town located in the southeast of the Sarmiento valley.
The Colhué in the 1970s was a great place for sport fishing and also for commercial fishing, the fishermen who sold in the village took their livelihood from the Colhué. The lake gradually lost its commercial fishing, which used boats. The economic activity originated by fishing became important despite the fact that it was carried out in a swampy body of water, with murky, shallow waters, which froze during the winter and suffered great drops. The reasons for the success of the fishing activity were due to the fact that the lake was navigable most of the year with simple boats, as it was not very dangerous due to its shallowness. This meant that during windstorms, the lake did not generate the strong swell of its neighbouring Musters, which, despite its smaller size, is deeper. Another factor in the success of the fishery is explained by scientific studies that analysed the silt and zooplankton in the lake in the 1980s. The findings led to it being labelled as an oasis of productivity around an arid territory. Being shallow (an average of two metres during the studies), the wind caused the soil to be stirred up, so the water had more nutrients, which in turn generated a large amount of zooplankton of a significant size (among the largest of the Argentinean lakes). This contributed to the abundance of food for perch and silversides, which in turn prevented them from preying on each other.
In the 1990s the lake could be seen to be moving further and further away. When the drought hit in the 2000s, the nearby ranches were gradually covered with sand from the lake, depopulating the area. Fishing, which had flourished in the 1970s, continued towards the end of the 1990s with exports to other cities in the region. It ceased to be received because the fish tasted muddy due to the continuous lowering of the lake. Thus, the modern fishing that began among the settlers shortly after arriving and settling on its banks and nearby came to an end. However, it left numerous traces of its activity all along the shore: boats, old moorings, settlements and some houses. The last fishing activities were carried out in the year 2000 during a great low water. Today, many of its fishermen have moved to the neighbouring lake.