The stunning tourist attraction near the Styrian village of Tragöß was at one time particularly popular among divers as every year the lake floods and rises to cover trees, benches and a bridge, creating a temporary underwater world.
In 2014 it was even voted "Austria's most beautiful place" in the TV show "9 Plätze - 9 Schätze" (9 places - 9 treasures).
Photo: Martin Toedtling/Wikimedia
But locals say the famously clear waters are becoming increasingly opaque due to higher levels of algae. Although the exact reason for the change is unknown, some believe the algae is a result of both warmer winters and the high numbers of tourists visiting the beauty spot.
“Strong tourism and a shortage of toilet facilities,” are two possible reasons given by Hubert Sulzer from the local mountain and nature rescue services.
The group is demanding better management of the high number of tourists to the lake, which in the last year alone saw around 100,000 visitors. Divers and swimmers have been forbidden from the lake since January 1st this year, in a bid to maintain good water quality.
Gerald Weninger, from the Tragöß Tourism Association and who has lived in the area for 20 years, told the ORF, however, that he thinks the problem of the water quality will solve itself again in a few years.
“If it becomes cold, the algae goes away again. It always comes back after a warmer winter. But during a subsequent winter with minus 10, minus 20 degrees Celsius, it will die again. I think that the problem will solve itself,” he said.