Fifteen days after large quantities of raw sewage began flowing into a lagoon in Juchitán, Oaxaca, the fetid odor has become overwhelming, driving away tourists and shutting down businesses.

A failing drainage system in the Isthmus of Tehuantepec city led residents of one neighborhood to pump untreated wastewater directly into Laguna Superior, while sewage is also flowing into the lagoon via local waterways.

The Los Perros river is contaminated by untreated sewage from at least six neighborhoods in Juchitán, where the only wastewater treatment plant hasn’t been operational for years.

The stench of the sewage is overpowering anywhere within the vicinity of the lagoon while from the community of Playa Vicente, a 300-meter-wide black stain is visible on the surface of the water, according to a report in the newspaper El Universal.

The contamination has caused oxygen levels in the lagoon’s water to drop, killing fish and triggering the proliferation of seaweed.

Local official Fernando Santos said that fishing has been suspended in the lagoon and businesses located on the shore have closed because there are no tourists.

Residents have grown desperate because their sole sources of income have been cut off, he added.

After inspecting the contamination during a flyover of the lagoon, the Oaxaca environment secretary warned that people’s health could also be at risk.

“From above, you can see perfectly the black stain of sewage that flows [into the lagoon] from the Los Perros river and from a Juchitán drainage stream. The contamination is terrible and alarming, that’s what’s causing the bad smell . . . We could have a serious disease outbreak if the situation isn’t dealt with urgently,” Samuel Gurrión said.

Rubén Dario Hernández, director of public works on the Juchitán council, said earlier this week that authorities are currently “working on a project to repair the wastewater treatment plant and to build two more so that the wastewater that is dumped into the Los Perros river is treated beforehand.”

However, he conceded that the project “will take time.”

Biologists from the Oaxaca Environment Secretariat and the University of the Sea (Umar) have collected samples of both water and seaweed from the lagoon, which will be tested before reports are issued.

Umar biologist Ivonne Santiago told El Universal that water samples taken from near the lagoon’s shoreline contained just 0.2 milligrams of oxygen per liter, well below the normal level of 5 milligrams per liter.

Source: El Universal (sp)