Similar to the slope of Mund there are also several irrigation channels on the slope of Birgisch, conducting water from the river Mundbach over the dry slopes near Birgisch. The two most famous bisse are «d‘Grossa» and «d‘Oberschta». «d‘Oberschta» is the uppermost bisse on the left side of the valley, therefore its name. The exact age of the «d‘Oberschta» is unknown, but the «Gärtneri» is first mentioned in 1435, which indicates that «d‘Oberschta» was created some years earlier. On the first section the bisse carries along its own water as well as the water of the «Gärtneri». It is recommended to carry on for the hike along the «d‘Oberschta» a flashlight (or a mobile phone with light), since it leads through long and badly illuminated tunnels.