| CERRON GRANDE RESERVOIR, El Salvador
CERRON GRANDE RESERVOIR, El Salvador An
artificial lake in El Salvador brimming with sewage and
industrial waste is mystifying scientists by attracting
thousands of migratory and sea birds.
Built in 1974 to drive El Salvador's biggest hydroelectric
project, the 33,360-acre (13,500- hectare) Cerron Grande
reservoir collects some 3,800 metric tons of excrement each
year from the sewage pipes, as well as factory run-off and
traces of heavy metals like chromium and lead, the government
So scientists are puzzling over the fact that some 150,000
seabirds from more than 130 species have chosen to make the
reservoir their home. At least 90 of the species are migratory
birds arriving from as far away as Alaska.
"It's one of the most contaminated lakes we have, which is
why we should carry out a study on why the birds are here,"
said marine biologist Oscar Molina.
Waste from 54 industrial plants, 55 coffee processing
plants, seven sugar mills and 29 sewerage systems flows into
the reservoir, the environment ministry found in a 2004 study.
Yet the birds attracted to the lake even outnumber the
roughly 100,000 people living in villages around it.
On one of 28 islands dotting the reservoir, biologists
discovered 46 nests made by migrating American storks who
produced some 100 chicks at the start of the year.
Biologists have been monitoring bird numbers at the
reservoir since 2001, but Molina said El Salvador lacked the
funds to carry out a full investigation into why so many are
attracted to the area.
Environment ministry ornithologist Ricardo Ibarra said
birds may be attracted by the sandy beaches, crawling with
insects, that appear around the edge of the lake in the dry
"The most relevant thing is why the stork is nesting here
for the first time," Ibarra said.
But the contamination is bound to be harming birds that
feed and nest there, possibly making them too weak to be sure
of making their migratory flights or affecting the strength of
the shells of their eggs, he warned.
In a worrying sign, agronomist Edgardo Erazo, who studies
wildlife on the reservoir, said scraps of plastic and metal --
and even plastic clothes pegs -- had been discovered in bird
nests around the lake.
(Additional reporting by Luis Galdamez)