Vacationers on the shores of Lake Ypacaraí.
Crédito: La Nación newspaper.
The Contaminated \"Blue Lake\"
Por Alejandro Sciscioli
Fecal coliforms, organic material, phosphorous and nitrogen pollute Lake Ypacaraí, the main attraction for travelers in Paraguay outside the big cities. The results of a study of the lake by a Japanese aid agency are soon to be released.
ASUNCION, Sept 3 (Tierramérica).- "One warm night we met, along the blue lake of Ypacaraí," begins Paraguay's most famous folk song. The lake is the country's main tourist destination outside the cities, but faces growing pollution -- denied by the authorities, but confirmed by new studies.
Fifty km east of Asunción, Ypacaraí ("lake of the Lord" in the Guaraní language), has a basin of 1,017 square km, and draws thousands of summer vacationers each year.
According to the National Tourism Secretariat, during this last summer season, more than 300,000 people visited the "summer village" of San Bernardino, on the lake's shores. Across the lake is the city of Areguá.
The greater watershed is fed by four smaller ones, comprising the Yukyry, Pirayú, San Bernardino and Areguá rivers. The lake discharges into the Paraguay River through the Salado River. Ten percent of the country's inhabitants -- around 600,000 people -- live in its area of influence.
Eighty percent of that population lives along the Yukyry, "which is lucky, because before it flows into the lake, there is the Yukyry marsh," says Elena Benítez, head of the environment ministry's water resources division, SEAM.
Benítez explained to Tierramérica that "the wetlands act as filters of the organic material" in the sewage water that finds its way into the river.
The number of Paraguayan households with access to sanitation systems is very low: 22 percent in Asunción and the metropolitan area, and just 10 percent in the rest of the country, said the official.
"The rest is dumped directly into the courses of water or the underground reservoirs through septic tanks," Benítez said.
In the Ypacaraí basin, SEAM has recorded 145 active industries, including slaughterhouses, soap factories and tanneries. Also functioning in the area are three large public hospitals.
The agency does not have data on the volume of industrial waste and sewage water discharged. "The statistical study is being conducted now," said Benítez.
But "it is no secret that for more than 30 years (Lake Ypacaraí) has had fecal coliforms," although, she said, "if we monitored the entire area we could say that, on the mean, it isn't contaminated."
However, the Japanese International Cooperation Agency (JICA), "found indications in 2000 of the existence of some algae that could be toxic," added the official.
In January, in the middle of the summer tourism season, a great deal of foam appeared in the middle of the lake, while the JICA report was being made public, which prompted the environmental prosecutor Isacio Cuevas to intervene.
Cuevas ordered three tests by the laboratories of the Ministry of Agriculture and Livestock, the National Institute of Technology, and the Ministry of Health, he told Tierramérica.
They found "fecal coliforms, chrome and mercury, among other substances, but at insignificant levels," said Cuevas, adding with a note of irony: "looking at these studies, I myself would go swimming in the lake."
The environmental prosecutor hopes to compare those data with the results of a fourth series of tests by experts from the JICA office n Brazil of the greater Ypacaraí basin.
Hideo Kawai, the scientist leading the Japanese agency's study, told Tierramérica that the results are not yet available, but he did mention the finding of concentrations much greater than acceptable limits of fecal coliforms, organic material, phosphorous and nitrogen.
The lake's waters are very rich in nutrients, which favor the rapid reproduction of toxic cyanobacteria, like microcystis aeruginosa -- blue-green algae -- found in Ypacaraí.
Kawai explained that the algae produce a carcinogenic toxin that can damage the human liver if a person is consuming the lake's water on a regular basis. But he added that in the potable water that has been processed by the state-run sanitation company Essap, there is no sign of microcystis.
Eighty-seven percent of the population of the Asunción metropolitan area has access to the potable water systems.
When the studies are concluded, Kawai will make a series of recommendations to the Paraguayan authorities, which will include the execution of a master plan and a search for technical and financial resources for treating sewage, the main factor no contributing to the reproduction of cyanobacteria.
Furthermore, it is recommended that residents and tourists avoid direct contact of the skin with the lake's water, he said.
Miguela González, owner of a weekend home in San Bernardino, told Tierramérica that she does not allow her children, ages seven and 10, to swim in the lake. "Now, with the algae, it is much more dangerous than it used to be," she said.