Lake Atitlán (Spanish: Lago de Atitlán) is a lake in the Guatemalan Highlands of the Sierra Madre mountain range. The word Atitlán means “at the water” in Nahuatl. It lies in a spectacular setting in the central highlands at about 5,128 feet (1,563 metres) above sea level. The lake, 1,049 feet (320 metres) deep, is 19 km long and 10 km wide, with an area of 127.7 square km. The lake basin is volcanic in origin, filling an enormous caldera (enlarged form of the volcanic vent) formed by an eruption several thousand years ago. The lake is renowned as one of the most beautiful lakes in the world, and is Guatemala’s most important national and international tourist attraction. The shores of the scenic lake are flecked with Indian villages. The main towns along the lake, including Panajachel, Atitlán, and San Lucas, are popular with anthropologists and tourists.

Geological History

The first explosive activity in the region occurred about 11 million years ago to be exact, and since then the region has seen four separate episodes of volcanic growth and caldera collapse, the most recent of which began about 1.8 million years ago and culminated in the formation of the present caldera. These volcanic activities are responsible for shaping the landscape, and that role continues to this day. Evidence of the continuing action can be found in the three volcanoes that serve to adorn the beauty of the Lake Atitlan area. These volcanoes are known as Volcan San Pedro, Volcan Atitlán, and Volcan Toliman. The last two are active volcanoes (active volcanoes are those which constantly eject volcanic lavas, gases, ashes and fragmental materials). During the last 10,000 years Atitlán has developed almost entirely and still remains active. The most recent eruption occurred in 1853. The earthquake in 1976 which killed 26,000 people caused significant subsurface drainage from the lake, allowing the water level to drop two meters within one month.

Ecological History

In 1955, the area around Lake Atitlán became a national park. In the late 1950s, the Guatemalan government introduced non-native black bass into the lake’s waters believing that hotels and restaurants could lure more tourists if they could offer freshly caught lake fish on their menus. Over the years, however, the bass ate through nearly the entire food chain, including the young of the rare Pato Poc duck. Their consumption disrupted the ecosystem and destroyed the organisms (led to the extinction of the Atitlán Grebe, a rare bird) that would have kept the bacteria at bay. The situation was aggravated by government distribution of chemical fertilizer containing extra phosphorous to poor farmers who liberally apply it to their fields. A phylum bacterium, cyanobacteria (it can produce cyanotoxins and reproduces explosively under certain conditions which can be harmful to other species, including human beings) was first detected by scientists in 1970’s and again recently in 2009 and 2015.

The lake Atitlán is an important tourist destination and a destination for several Guatemalans to earn their livelihood. Urgent steps need to be taken to cut the sources of pollution and make it suitable for human beings again.

Ecological History