The Kollauteich is an approx. 0.63 hectare pond or retention basin in Hamburg-Schnelsen near the A7.
It is in the Vielohwiesen.
It is a remnant of the "Düwelsmoor" (high German Teufelsmoor), a muddy lake that dried up in the Middle Ages.
Another remnant of this lake is the Teufelssee on Bönningstedter Weg, which has now been artificially changed.
Since 2011, the Kollau has been diverted past the Kollauteich so that the course of the stream is not interrupted.
At high water, when the Kollau overflows its banks, the pond serves as a retention basin for the Kollau.
The Kollau pond is often mistakenly treated as the source of the Kollau.
However, this is not correct, as the Kollau already runs approx. 450 meters to the Kollauteich and has its source at the source pond on the Vielohweg on the other side of the A7.
The only tributary of the Kollauteich is the Dübwischgraben, which is officially a tributary of the Kollau.
This is due to the fact that the Kollauteich, as a retention basin, is temporarily connected to the Kollau and water exchange takes place as a result.
(Source: Wikipedia)