More than just causing a big stink, the deaths of thousands of fish in a high Andean lake have prompted local officials to declare an environmental emergency.

Since Friday, officials have removed more than two tons of dead fish from Lake Sochagota, an artificial body of water and one of the primary tourist attractions in the town of Paipa, Boyacá.

“Some parts of the lake are still healthy,” explained Luis Fernando Pinzón, municipal emergency and environmental disaster coordinator for the town of Paipa.

“So we’ve been working to clean up the rest of lake and remove dead fish while we work on longer term solutions.”

It’s not the first time fish have died off en masse in Sochagota. In February and March, similar situations had local authorities on alert, and all aquatic activities have been suspended for two months, according to Pinzón.

More than six tons of dead fish have been removed in total so far this year.

“The lake wasn’t designed to support fish,” said Pinzón. “It was built to clean some of the salt out of water from nearby hot springs before it reached the Río Chicamocha.”

Experts with Corpoboyacá, a government organization dedicated to protecting the environment in the Boyacá department, are still waiting on test results to confirm the cause of the most recent die-off.

But officials believe the troubling levels of fish mortality are due primarily to low levels of oxygen in the lake’s waters, which in previous tests have registered well below quantities necessary to sustain aquatic life.

Neighboring bodies of water, which typically help oxygenate Sochagota, have been hard hit by a particularly strong El Niño system. Sochagota itself has seen water levels drop dramatically over the past year.

So even though rains have started to return, there’s not nearly as much flow between Sochagota and other water systems as there has been in times of more plentiful rainfall. And the new water may be bringing new problems.

“Low water levels were the problem last year and until the past few months, said Ivan Bautista, head of ecosystems management with Corpoboyacá. “Now new water is entering the lake, but it is bringing with it contaminants that have built up in the surrounding land during the drought.”

Making matters worse, hotels surrounding the lake have been accused by the Paipa mayoral office of dumping untreated sewage into its waters. Recently elected Mayor Yamit Hurtado threatened to revoke the license of any business caught in the act.

“So far, no hotel has been found dumping water into the lake,” said Pinzón. “Two nearby cabins are being investigated, but we don’t think sewage is the primary problem.”

Pinzón explained that various clean up and water quality improvement efforts are underway, and environmental officials hope to have at least 70 percent of Lake Sochagota recuperated by November.