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Lake Matano: The Deepest Lake in Indonesia

lakeLake Matano
countryIndonesia
surface area161 km2
maximum depth590 m
average depth62 m
lake typeTectonic
length28 km
width8 km
catchment area436 km2
altitude394 m
volume10 km3
outflowsPenten River
shore length91 km
residence time4,538 days
trophic stateOligotrophic
originTectonic
average discharge26 m3 / sec.

Lake Matano Information and Facts

Lake Matano is a tectonic lake in the South Sulawesi. It is the deepest lake in the country and the tenth deepest in the World.

Geography and Chemistry

Lake Matano is one of the two major lakes in the Malili Lake system, the other being Lake Towuti. It is drained by the Patea River, which makes its way into Lake Mahalona of which it is separated merely by a waterfall. The lake is between 1 and 4 million years old, and because it’s been isolated from other lakes, it has a rich and unique ecosystem. Its remote location (600 kilometers southwest of Makassar), and the thick lush forests on its shores made sure that Matano remained a pristine and hard-to-reach tropical paradise.

Lake Matano was named after one of the fishing villages on its coast with the same name.  It means “wellspring” in the local native tongue.

Below the surface of Lake Matano, which is an oxygenated layer, its depth is anoxic, free of sulfates and rich in iron. These contribute to the lake being an analog for Earth’s oceans during the Archean Eon, which is useful for analyzing the relationships between anoxygenic and banded iron formations. The lake is also home to a population of green sulfur bacteria, which conducts photosynthesis with bacteriochlorophyle E.

Ecosystem

Because the lake is so isolated, it boasts a richness of endemic plants and animals. 60 endemic mollusks, more than 25 endemic fish, 10 types of endemic shrimps and three endemic crabs inhabit the lake waters. The local endemic fish were compares to those of the Rift Valley Lakes of Africa, even though they are not as diverse. They are all thought to originate from a single ancestor species, which diversifies into plenty of different subspecies. The only imported species is the eel.

Because of the curious development of the fishes in the lake, and the unusual high-iron concentration in the lake, Matano is often subject to scientific studies. However, many endemic species are threatened by the pollution of the area and predation from introduced species like the Flowerhorn Cichlids.

Threats

Although Lake Matano is located in a remote location, it is also the site of the PT Vale Inco Indonesia Tbk, one of the biggest nickel mines in the World. It carries out strip mining in the surrounding rainforest. Even though the company has a well-regarded rehabilitation program as well as an award-winning control system, and it replaces the rainforest with monoculture, specialists fear that these actions will lead to the loss of biodiversity in the region.

Numerous fish rely on the high visibility of the lake when breeding, but because of the sediment increases in the lake, this will likely cause problems. Deforestation causes run-offs, which, in turn bring on a higher probability of eutrophication to the lake.

The company would also build a dam to generate hydroelectric power downstream, between Lake Mahalona and Lake Towuti, providing electricity to local towns and villages. Government forces encourage people to move from the lake’s crowded northern shores to the southern coast, keeping the place in balance.

Tourism and Recreation

Though the lake is pretty remote, it’s not impossible to get there. One can either take a 12-hour bus ride or a very expensive flight from the nearest largest city. But the ideal way to reach Lake Matano is by car. The sparsely advertised hotel in Sorowaks is the only internationally known accommodation site on the lake’s shores, but one can contact a local travel agency which will help with finding good accommodation.

The lake represents a major highway for local villagers, who row from one community to another. Commercial cruise boats have regular trips between Sorowakol and Nuhu. Waterskiing, canoeing, diving and rafting are popular water sports activities, which can be rented from locals. A private yacht club exists for members only, used mainly by the employees of the nickel factory. Several underwater caves await enthusiastic divers.

Lake Matano Fish Species

Eel