Kiesgrubensee Gremberghoven

The lake occupies most of the former pit; a small island rises from the water in the northern section. The shoreline is narrow, sandy-gravelly, and largely free of vegetation. Behind it, steep pit embankments rise up, supporting pioneer vegetation alongside mosses, fungi, and lichens, as well as planted shrubs. The eastern slope in particular displays pronounced escarpment collapses and open bare-soil areas. The predominant water body types are oligotrophic to mesotrophic calcareous lakes with benthic vegetation, including several species of stonewort algae.

The reserve is home to numerous plant species, including aquatic plants such as spiked water-milfoil, hair-leaved pondweed, fennel pondweed, and rigid hornwort, as well as pioneer species of bare-soil areas like coltsfoot, Canadian fleabane, and common mouse-ear. Woody species such as hornbeam, goat willow, silver birch, and Scots pine are also present.

The main threats to the site include recreational activities, fly-tipping, pollution, and unnatural water management. Protective measures include fencing off sensitive areas, restricting fishing and other leisure use, and removing litter. Parts of the site are also deliberately left to natural succession in order to preserve the lake as a habitat and stopover for migratory waterbirds.