MARACAIBO, Venezuela (AP) — The fishermen of Lake Maracaibo say they face their worst nightmare everyday as fish stocks decline and pollution degrades the health of this great freshwater lake, one of the oldest — and largest — in the world.

Lake Maracaibo, which once was at the heart of Venezuela’s oil boom, has turned into a polluted wasteland, according to environmentalists.

The pollution of the lake, located about 600 kilometers (372 miles) west of the capital, Caracas, is the result of decades of excessive oil exploitation, poor maintenance of the obsolete infrastructure and a lack of waste treatment plants in the area. Tens of thousands of kilometers of pipes lie at its bottom, where crude oil leaks and system failures are frequent.

The lake, which collects rainwater from more than a hundred tributaries, has also become the wastewater deposit for the western states of Zulia, Mérida and Trujillo, where 5.3 million people live. Waste from the Colombian department of Norte de Santander also ends up in it.

Fertilizers, sewage and other chemicals are discharged into Lake Maracaibo, causing high concentrations of nitrogen and phosphorus that have led to the growth of cyanobacteria such as microcystin that produces 95% of what is locally called “verdin,” a greenish, toxic microalgae that occupies much of the lake’s waters, according to Beltrán Briceño, a professor at the University of Zulia and head of the microbiology laboratory of the Institute of Agricultural Research in Maracaibo.

The proliferation of cyanobacteria can cause serious damage to both aquatic animals and human beings due to the toxins they generate, he said. Cyanobacteria can cause massive fish deaths.

The fish no longer come near the shores of the lake because the microalgae “drowns them,” said José Aular, a 61-year-old fisherman who says he developed a skin rash because of the lake’s contamination.

Environmentalists say oil pollution in Lake Maracaibo began at the beginning of the 20th century but worsened in the early 1930s, when a canal was excavated at the northern end of the lake to allow large oil tankers to navigate and connect the lake with the open sea. Seawater flowed in, killing freshwater wildlife, such as some plants and fish.

Before, “you would go out fishing and catch 700 kilos (about 1,500 pounds) of shrimp” almost all the time, said Yordi Vicuña, a 33-year-old fisherman. Now, he says, fishermen spend days at sea only to come back with about eight kilos (17 pounds) of shrimp.

Fishermen can’t cast their nets anywhere because they will get damaged. Crude oil spilled into the lake smears fishing boats, clogs outboard motors and stains nets, said Vicuña.

The pollution of Lake Maracaibo is decades old, but now it’s being felt on its coast with its bad smells, oil spills and microalgae, said Briceño, the professor at the University of Zulia.

“There is no magic formula” to rescue the lake if it continues to be used as a “septic tank,” he warns.


Associated Press writer Jorge Rueda contributed to this story from Caracas, Venezuela.