Zankwieser Teich, Reservoir in Germany

Zankwieser Teich is a historic reservoir about two kilometres northeast of Zellerfeld, a district of Clausthal-Zellerfeld. Its earthen dam, built of locally quarried stony material and sealed with turf sods on the water side, has a sharp 90-degree bend on the left (eastern) slope, indicating that the dam was raised at least once. The reservoir holds 113,000 cubic metres of water.

The reservoir was built in 1688 to supply water for mining operations in the region, used for washing and processing ore. In 2010, the entire Oberharzer water system that includes this pond was designated as a UNESCO World Heritage Site.

The pond lies in the Spiegelbach catchment and feeds, via the small Striegelwiderwaage reservoir and the Zankwieser Grundgraben, the Kiefhölzer Teich; from there the Zellerfelder Kunstgraben carried its water to the Zellerfeld mines as Aufschlagwasser. In summer it is popular as a bathing pond, and because of its remoteness it is often used for nude bathing.

The site is easily reached from Clausthal-Zellerfeld by driving about 2 kilometers north and following signs toward Festenburg. A free parking lot at the nearby Kiefhölzer Teich provides a short 300-meter walk through woodland to reach the reservoir.

The dam has a sharp 90-degree bend on its eastern slope, and the historic spillway sits in the right third of the dam rather than on the far right slope where solid rock would have allowed a firmer foundation. Both point to the dam having been raised at least once, though the date is unknown.