Since 2019, BOKU Vienna (Dr. Erwin Heine) and the Munk Foundation have been conducting research in Lake Altaussee. Using state-of-the-art measurement techniques, the lake has been surveyed and studied from both hydrobiological and microbiological perspectives. A 3D model of the lake basin was also created, revealing in high detail sediment formations, large rocks, and around 100 submerged tree trunks.

Some of these trees have been known since the 1970s: in 1997, divers from Altaussee cut and recovered small tree discs. In the U.S., the C24 method was used for precise age determination — and the results far exceeded initial estimates: the trees had been underwater for an astonishing 1,300 years!

A particularly massive tree trunk was recently recovered for closer examination by the Altaussee water rescue team. Using a tractor winch, the trunk — located about 100 meters from the shore at a depth of 18 meters — was pulled over. Three lift balloons brought the roughly 4.5-ton relic to the surface, where it was towed to shore by the fire brigade’s boat.

Our forestry specialist, Manfred Ainhirn, removed the rootstock and then cut a tree disc approximately 15 cm thick and over 100 cm in diameter. The tree disc, along with sediment from the root area, was sent to Vienna for detailed analysis.

Researchers hope the findings will shed light on how the trees ended up there. Currently, there are two main theories:

• Either the trees were swept into the lake by natural events such as avalanches or landslides and then sank,
• or they originally grew on-site, and the lake was dammed to its current level by a tectonic event around 700 to 750 AD.

Which ever the case, the results are eagerly awaited…