Segelbach Reservoir

As of February 27th, 2022, the water has been drained and access to the lake is blocked.

This flood retention basin between Weil im Schönbuch and Waldenbuch was officially put into operation in August 1982. After severe flood damage in the Aich catchment area in August 1966, September 1968, February 1970, June 1971 and especially in May 1978, this reservoir was built to prevent similar disasters in the future.
The approximately 1.5-hectare lake holds around 47,000 cubic meters of water at a depth of almost seven meters. Should flooding occur again, the lake can hold back five times the amount of water and thus help prevent damage.

Source: naturpark-schoenbuch.de

Currently, the water is drained for maintenance. You can see how deep the pelvis is actually. Entering the area is prohibited because of danger to life by sinking.