Diez is an abandoned quarry, lying in a valley close to the river Lahn. After the pumps have been switched off, groundwater filled the lake. The ground is at two levels: In the front part around 8m, in the back part around 15m. “Baggersee Diez“ is used as a recreational area, where in summer hundreds of people come to swim and enjoy the sun. It is well known for its good visibility and lots of divers meet during the weekends to enjoy diving.
We installed 3 secchi disks to measure the visibility in different parts of the lake: From shallow to deep and from places that are regularly dived to places hardly dived. We can see, which influence diving has on the visibility (and with this on the plants covered by silt) and how the visibility changes in winter at different depths - in cold water algae disappear. Baggersee Diez is an abandoned querry which is fed by groundwater. It is used for diving and swimming as well.