The Lake That Appears and Disappears

Legend has it that there is a strange little mountain lake in the province of Trento that is almost magical because it appears and disappears. It was said that this lake came into being, and later that the earth opened up and swallowed an entire village with its small church; that specters and evil spirits would visit it. This is Lake Andalo, which has no inlet or outlet; it is fed by mysterious underground currents that, during the summer, leave it almost completely dry. The small Lake Andalo is located at an altitude of approximately 1,000 meters, at the foot of Mount Piz Galin. It is of karst origin, with a length of about 1,450 meters and a depth of 13 meters, but its size changes depending on the season: in spring and autumn, the water level is higher, while in summer it can shrink significantly or nearly disappear, making way for a grassy meadow. In spring, when the snow melts, or in autumn, when rainfall is more abundant, the basin fills up, and consequently, the surface area of the water expands. However, during other seasons, such as summer, the water may vanish. This occurs because the lakebed was once rich in small pebbles of glacial origin, which over the years have disappeared, giving rise to the phenomenon of the periodic lake. There are only eight lakes in the world affected by this phenomenon, and Lake Andalo has no visible inlets or outlets; the water exchange happens underground. At the beginning of the 20th century, it was believed that the lake drained its waters into the nearby Lake Molveno when excessive rainfall damaged crops, giving rise to the local proverb: When the water of Lake Andalo flows to Lombardy, seven years of famine await.. Today, we know that Lake Molveno is an alpine lake of natural origin, formed about four thousand years ago as a result of a massive landslide that blocked the valley. It is the largest lake above 800 meters in altitude in the region, with a surface area exceeding 3 km² and a depth of over 120 meters.