Lake Wolayer
The Lake Wolayer is an Austrian mountain lake on the Carinthian side of the, near the Plöcken Pass. It is the centrepiece of the Wolayer See and surrounding area nature reserve. Notable plant species include Alpine eryngo, sweet cicely, and Austrian ribwort.
The lake lies at an altitude of above sea level and covers an area of 4 hectares. It is located in a doline formed tectonically and reshaped by the Wolayer Glacier during the Ice Age. The catchment area spans approximately. Annual rainfall in the region ranges between, maintaining a relatively constant water level despite the absence of surface inflow. The lakebed is covered with mud, which seals the lake. The western part of the lake slopes gently, while the eastern side is steeper. The deepest point is below the surface, but two-thirds of the lake is less than deep. Water that flows underground from the lake feeds two springs: one in Austrian territory and another in Italian territory, south of the Lambertenghi hut.
Physical and chemical parameters
The surface water temperature reaches a maximum of 14 °C. Stable temperature stratification does not develop in summer due to the lake's wind-exposed location, situated only below the Wolayer Pass, where strong winds blow. The lake is frozen for six to seven months each year, with a multi-layered ice cover reaching up to thick.The lake water is slightly alkaline, with a relatively low electrical conductivity of less than 100 μS/cm. The acid-binding capacity is low, at less than 1.3 mval/L, and the lime hardness ranges from 3 to 4 °dH. Nutrient concentrations are low. Organic matter is primarily introduced through the air.
Biology
Due to the low nutrient concentration, the amount of suspended algae is minimal, measuring less than.Like most high mountain lakes, Wolayer See is naturally fish-free. However, in 1976, fifteen brown trout were introduced, significantly reducing the population of lake fleas. The trout initially thrived but became stunted after a few years due to starvation. In 1980, 4,000 char and brook trout were introduced. These fish also reproduced successfully at first but later became stunted due to starvation, a condition known as "black reiters".
There is largely no siltation zone or aquatic vegetation. Marsh plants occur in a few shallow areas, including narrow-leaved cottongrass, marsh marigold, spring saxifrage, marsh willowherb, and rush species such as Juncus filiformis and Juncus triglumis.