The "Kleine Weser Weir" river dam is located in the immediate vicinity of the city center in the heart of Bremen in the Kleine Weser, a branch of the Weser, between Teerhofinsel and Neustadt. The facility is maintained and operated by the Bremen Deichverband on the left bank of the Weser for the Free Hanseatic City of Bremen.
The weir serves to maintain the Werdersee. The structure achieves an almost constant water level that is independent of the tides. This makes the Werdersee very popular with citizens in all seasons as a central element of local recreation and invites outdoor activities.
In addition, the weir has an important function in the flood protection system. In the event of flooding from inland areas, part of the flowing water is diverted via the Werdersee and the Kleine Weser, thus relieving the Middle Weser. In this case, the outflow is controlled by the movable segment flaps of the weir. In an exceptional case, the so-called n-0 case, the weir can be subjected to a discharge of up to 1,200 m³/s. The entire discharge cross-section can then be released by lifting the two weir flaps.
The dam was built and put into operation at the end of the 1960s. It is a weir system consisting of two weir fields, each with a clear width of 24 m.
The total width of the system is 57 m, the total length in the direction of flow (without the bed reinforcements and bank edgings on the upstream and downstream sides) is around 20 m.
The central pillar is around 10 m high, 3 m wide and around 19 m long. On both sides of the weir system, on the edge pillars, are the operating buildings in which the technical equipment for driving the weir flaps is housed.
The system was supplemented in 1999 with a fish pass. This was retrofitted as an extension of the Neustadt-side circulation channel. The fish pass is equipped with two gates in the openings above and below the water. The Teerhof-side circulation channel is closed by a gate mounted in a shaft.