Lyssbach, Brook in Seeland district, Switzerland

The Lyssbach is a small waterway that flows through the Seeland region in the canton of Bern, passing through several municipalities across agricultural land. This stream forms part of the broader water management infrastructure that supports the area's farming communities.

The Lyssbach was first documented on 10 August 1275 as "Lissa", when knight Ulrich von Buchsee confirmed handing land up to the Lyssbach bridge at Schwanden to the Knights Hospitaller. From the 1970s the stream was channelled and the valley wetland drained. After repeated flooding in Lyss, a flood relief tunnel was bored from 2009 to 2011 to divert high water around the town.

The stream's name comes from the 1275 document in which the knight Ulrich von Buchsee confirmed handing his land up to the Lyssbach bridge at Schwanden to the Knights Hospitaller. The mills and oil works once driven by its water are recalled by the Gewerbekanal near Suberg, and the Wasserbauverband Lyssbach, founded in 1987 by five municipalities, still manages the brook.

The stream is culverted for much of its first stretch from Moosaffoltern down to the Lyssbachtal, surfacing only for about 160 metres at the hamlet of Lätti. Walkers see it above ground mainly from Schönbrunnen onward, where it runs along the northern valley floor beside the Moos. Near Suberg a side channel leads to the old oil-mill and mill waterworks.

The stream's name was first recorded on 10 August 1275 as "Lissa", in a deed by which the knight Ulrich von Buchsee confirmed he had handed his land up to the Lyssbach bridge at Schwanden to the Knights Hospitaller. The brook powered mills near Suberg, where two more mills once stood below the village.