Wasserbaum Ockensen, Natural monument in Salzhemmendorf, Germany

Wasserbaum Ockensen is a natural monument consisting of a moss-covered wooden pipe with water continuously flowing from its top, supplied by a nearby mill pond. Over decades, mineral deposits have accumulated on and around the pipe, giving it the appearance of a tree trunk blanketed with green growth.

The wooden overflow pipe was built by sawmill owner Hermann Meyer, who ran a sawmill in Ockensen between 1904 and 1926. He had a mill pond created a few hundred metres uphill on the Ith, and the pipe let him see from the mill whether the pond was full enough to drive the turbine. Lime from the strongly calcareous water precipitated on contact with air and, together with mosses, turned the pipe into a moss-covered stump.

The name Wasserbaum ("water tree") comes from the moss-covered tuff cone that the overflow pipe has become. The pipe was built by sawmill owner Hermann Meyer so he could see from the mill whether the pond uphill at the Ith was full: when water spurted from the top, the turbine had enough. The lime-rich water deposits tuff and mosses settle on it, so the wooden core is now hidden inside a green stump.

The overflow pipe stands on the slope below the former mill pond, a few hundred metres uphill from the old sawmill site on the Ith. The ground near the outflow and the adjacent Im Heidsieke spring bog can be damp, so sturdy footwear helps. The calc-tuff coating and moss are part of the protected natural monument and should not be scraped off.

The pipe was built by sawmill owner Hermann Meyer so he could see from the mill whether the pond uphill was full: when water spurted from the overflow, the turbine had enough. The lime-rich water deposits tufa on contact with air, and mosses settled on it, turning the wooden pipe into a mossy stump.