Lower Grumbach Pond, dam in Germany, Closest city: Clausthal-Zellerfeld

Lower Grumbach Pond is a reservoir near Goslar built to store water for the region and surrounded by trees and fields. The water reflects the sky and changes with the seasons, while gentle walking paths run around the basin.

The pond was built before 1673 and was part of the historic water management system of the Upper Harz mining region. The dam was raised over time to store more water for mining operations and forestry.

The pond's name comes from the Grumbach stream that feeds it. Its water was released in bursts to carry one- to two-metre logs down to the Innerste, and a rafting ditch led timber around the pond to the Gefluder at today's Grumbach Waterfall. A refuge hut by the dam holds checkpoint 113 of the Harzer Wandernadel.

The pond lies between Hahnenklee and Wildemann in the Harz Nature Park; the Grumbacher Graben diverts most of the Grumbach inflow past the pond, so the water level depends on the diverted flow. A refuge hut by the dam holds checkpoint 113 of the Harzer Wandernadel hiking network. The dam is 7.5 m high and just under 60 m long.

The pond is the only Upper Harz reservoir with a small island of about 30 m² near the head of its impoundment, possibly a small mining spoil heap. It also had two wooden bottom outlets of 24/24 cm, later replaced by plastic pressure pipes.