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Laguna Catemaco Lago Catemaco
Location	Veracruz
Coordinates	18°25′N 95°05′WCoordinates: 18°25′N 95°05′W
Lake type	polymictic, eutrophic
Primary outflows	Rio Grande de Catemaco
Basin countries	Mexico
Surface area	72.54 km² (28.01 square miles)
Average depth	7.6 m
Surface elevation	340 m (1,115 ft)

Laguna Catemaco is a lake located at the center of the Sierra de Los Tuxtlas in south central Veracruz, in east central Mexico. In English the word lagoon generally describes a body of water exposed to the sea. In Mexican Spanish laguna seems to refer to that plus the word lake in general. Common usage in Mexico is Laguna de Catemaco, though scientific articles prefer the term Lake Catemaco (Lago Catemaco in Spanish).

Laguna Catemaco was formed millennia ago, when lava flow from Volcano San Martin Tuxtla blocked its current northern end, and stands now at 340 m (1,115 ft) above sea level. It is shallow, averaging 7.6 m (25 feet), with a maximum depth of 22 meters located in the channel between Isla Agaltepec and the city of Catemaco. The circulation pattern is clockwise. The laguna drains via the Rio Grande de Catemaco and its water level is controlled by several dams which replaced historic waterfalls. The change in water level is more than can be explained by evaporation and outflow. Apparently the laguna sits upon fissures permitting water to percolate down.

The lake is polymictic (water turns over more than twice a year), well oxygenated, and contains excessive nutrients (eutrophic) because of fertilizer runoff from the neighboring farms and nurseries. Because of the excessive nutrients, Laguna Catemaco is one of the more productive lakes in Mexico, up to 1,800 tons annually. Large netting is prohibited to assure the livelihood of hundreds of registered fishermen. A perch like fish introduced from Africa (Mojarra Tilapia), a sardine like Topote, and the snail Tegogolo are the most common catches.

Lake Catemaco has a surface area of 72.54 km² (28.01 square miles), is formed like an elliptical parabola and is almost square with maximum width and axis of a little more than 10 km (6 miles), (10,250 m width and a WSW-ENE axis of 12,320 m). It contains about 552 million cubic meters of water (420,000 acre feet). The laguna is Mexico's #18 in size of water bodies, #7 in size of lakes & lagunas, #3 in size of lakes.

Prevailing climate is hot and humid with average temperature of 23.4 °C (75 °F). Rainfall varies seasonally with averages of 2,068 mm (81 inches) recorded at Catemaco and 4,614 mm at Coyame. Winds from the Gulf of Mexico enter the Catemaco watershed through an opening in the surrounding sierra located to the north of the town of Coyame, and cross the lake in a NE-SW direction, blowing strongly over the lake throughout the year. From February to October, northeast winds are dominant. Colder and faster northern winds blow from November to January.

The tropical rainforest that once covered all the watershed of the lake has been severely decimated in the last few decades. Consequently sedimentation has greatly increased, affecting the clarity of its waters and if left uncontrolled will possibly fill in the lake in the far future.

The shoreline is irregular, with remnants of several volcanic cones and its perimeter is about 50 kilometers (30 miles) and would be an ideal venue for 50 km sporting events, if circumnavigation were possible. At present a gap in the lake shore road at Tepeyaga peninsula prohibits this.

There are several volcanic islands within the lake. Several of these islands are stocked with native and imported monkeys as a University of Veracruz research project. This has led to more than 70 small boats scurrying tourists from Catemaco city across the lake to view the islands' free ranging monkeys.

• tuxtlas.com: Laguna Catemaco