Lake Constance, the largest reservoir of drinking water in central Europe, has dropped to 394.21 meters above sea level — the lowest level in 135 years of records. The reading was taken at the Swiss town of Berlingen, in the Untersee basin, in late September, not in winter, when levels usually fall this low.

The Alps saw almost no snow this winter, rain has been scarce, and the heat has evaporated much of the water. Over the past 30 days, areas north of the Alps have had just 35% to 50% of the rain they'd normally get this time of year. On the hottest summer days, the lake fell by about half a centimeter a day. Water flowing into the area has dropped by more than 70%.

Harbors on the German shore near Radolfzell and the town of Moos have run dry. Tourists are told to check for restrictions at harbors before renting a boat or heading out for water sports, since some harbors have dried up completely.

Near Steckborn, in the Swiss canton of Thurgau, water plants and algae lie exposed and give off a strong smell. Fish are struggling with the low water, the heat and the lack of oxygen.

Locals and experts call the situation "dramatic." A local resident says much of the water is being lost to leaks, evaporation and use. No improvement is expected. The missing water can only come back through heavy snowmelt — at the earliest next summer, and only if enough snow falls.

A 75-year-old resident of Horn, a town on the Untersee, says he has never seen so little water there. You can no longer step into the water without getting mud on your feet.

Lake Constance lies on the Rhine, on the border between Germany, Switzerland and Austria, and is the largest lake in the Alps. It covers 536 square km, runs 63 km long and 14 km wide. Its deepest point, 254 meters, lies between the German town of Friedrichshafen and the Swiss town of Uttwil. Of its shoreline, 173 km lies in Germany, 72 km in Switzerland and 28 km in Austria. The lake's name dates back to antiquity, after the Roman emperor Constantius — either the first or the second — who lived in the 4th century.