In 1929, Lake Piburg was designated as a natural monument. Today the environmental reserve Achstürze – lake Piburg (since 1983) covers the surrounding area of the lake as well as the inner valley region “Achstürze” and lake Habich (a total of about 200 ha).
The creation of the lake goes back to a natural disaster. Initially, the bottom of the lake was an old valley that ran parallel to the Ötz valley. A massive rockslide cut the valley off after the last ice age, leading to the impounding of the lake. The forest growing on the boulders surrounding the lake still give testimony to this event. The water reaches a surface temperature of about 24°C in summer, whereas the temperature on the bottom (at a depth of 25 m) remains at about 4°C throughout the year. The comfortable water temperature and the soft pH are not only great for swimming, but offer conditions for a special habitat hosting many plant and animal species. Lake Piburg is probably one of the most researched lakes in Tyrol. Aquatic research has been carried out since 1931, and since 1975 there have been intense research programs with ongoing measurements carried out by the University of Innsbruck.