Kiesgrube Aitrach, Nature reserve in Aitrach, Germany.

Kiesgrube Aitrach is a 13.4-hectare nature reserve southwest of Aitrach's residential area, at 591 to 610 metres above sea level. Two gravel pits, now flooded, form lakes of about 2.5 and 2 hectares, up to 12 metres deep. Steep wooded walls surround them, with a raw gravel area colonised by willows in the middle and a secondary forest rich in deadwood in the west.

Gravel was extracted here until the site was designated a nature reserve by the Tübingen regional council on 17 October 2007 (NSG no. 4.318). The reserve covers 13.4 hectares, less than the 24.2 hectares planned in 1997, because part of the area was lost to a sports and leisure ground. The flooded gravel pits were left to develop without intervention.

The name comes from the gravel pit that operated here; the site is now a nature reserve where the former extraction area has been left to develop on its own. Visitors come for birdwatching and to observe the two groundwater-fed lakes, which stay largely ice-free even in hard winters.

The reserve lies southwest of Aitrach's residential buildings and the Turn- und Festhalle, at 591 to 610 m above sea level. The designated area ends directly at the south shore of the southern gravel lake; the southern slope was left out because a new route for Landesstraße 314 is planned there. Swimming, campfires and motor scooters are prohibited, and such use has disturbed breeding birds.

The two lakes are fed by the second-largest groundwater stream in Baden-Württemberg, which flows through the gravel-filled Tiefe-Aitrach channel at 20 to 30 metres per day. Because of this constant exchange, they rank among the coldest lakes in the state in summer and the warmest in winter, and stay largely ice-free even in hard winters.