Upper Harz Ponds

The Upper Harz lakes are some 70 smaller and larger storage ponds whose district Buntenbock and cock clover are placed in the Upper Harz mainly to the mining town of Clausthal -Zellerfeld. The ponds have been created artificially by Upper Harz miners mainly between the 16th and the 18th century. They are an essential part of the cultural monument Upper Harz Water Regale, and thus belong to the UNESCO World Heritage Sites. About half of the storage ponds is classified as dam building. However, they are now become a typical part of the Upper Harz and are home to some extremely rare plant and animal species.

The Upper Harz lakes are also the oldest still operating dams in Germany.

Purpose

The dams were originally built for the storage of water to drive water wheels to power the Upper Harz ore mines. With these water wheels, the operation of pumps, conveyor systems, the stamp mills and since 1820 also the driving skills was assured. The water ponds for storing won the first of their natural catchment area, which was then often considerably enlarged by additional drainage channels.

Today the ponds on the grounds of historic preservation, landscape management, nature conservation and recreation are operated. Some ponds are used for flood control, some other ponds are used for drinking water. Operator of the ponds are the Harzwasserwerke, which also operate six modern dams in the Lower Saxon part of the resin.

Architecture

The Absperrbauwerke are constructed as earth dams. The embankment fill material was usually obtained locally: Usually you put the future of storage space small quarries to where you thereby simultaneously increased the storage space. As sealing building materials no mud or clay could be used, since it did not exist in the Upper Harz in sufficient quantities. The Upper Harz miners but had found by experience that it is possible turf very well as sealing building material: agent such as masonry successive set turf a partial meter-thick layer was installed in the dam, which provided for the tightness of the dam.

As a bottom outlet acted a Holzgerenne, which was made ​​due to the longer shelf life usually of oak. Served as a so-called closure " harrow " which, like a plug locked the inlet opening of the Holzgerennes similar and could be pulled by means of linkage. Both turf seal, as well as wooden bottom outlet are still in the many ponds in operation.

The dams are 4-15 m high and the storage volumes of the storage ponds vary 10000-600000 m³. A special exception is the Oderteich is northeast of Sankt Andreas Berg, who was sealed as a single pond not with turf, but with granite screen and with a dam height of 21 m and a storage capacity of 1.7 million cubic meters of water, the dimensions of the remaining ponds significantly surmounted.

Flora and Fauna

Although the waters are artificially created, a rare flora and fauna has evolved in many Oberharzer ponds. It is nutrient-poor and rather cool still waters. The crayfish, which is extinct in most European waters due to the crayfish plague, has been able to survive in many Oberharzer ponds thanks to its isolated location. Operators and fishing tenants are successfully to strengthen the population.

The centuries- long operation with constantly changing water levels also has extremely rare plant communities provides a habitat: On many pond bottoms to find Lively cartilage chickweed, Hirschsprung or beach Ling. You are reliant on fluctuating water levels continue to be driven in the storage space and the nature conservation authorities have agreed with the operators of a business plan that ensures in the affected waters the stock of these plants. At other ponds there is small sedge.

The fish population is mainly influenced by the lease end fishing clubs that occupy the ponds with fish. Desirability, only native species of fish, especially eel and catfish stocking should be avoided because of the incompatibility with the crayfish stock.

Table of the Upper Harz Ponds

The following list comprises largely built by the Upper Harz miners storage ponds where these are still visible yet in operation or significant dam remains. Mill ponds are not listed. A total of 143 dams and former dams are documented.

(† ) means: pond out of service, mainly dry. Dam remnants are present. "T " means dam in accordance with Low Saxon Water Law.

Where no data are stored, the ponds are usually even before setting the mining industry gets into other hands and therefore not as precisely documented.