The beavers

The aim of the renaturation is to restore the Bieber to a good ecological condition. This concerns the water quality and the water structure of the Bieber. To this end, the Bieber will be restored to as near-natural a state as possible. Site-typical trees such as alders, willows and birches will be planted. The plants and trees along the Bieber shade the watercourse, help to regulate the temperature and reduce the risk of eutrophication, i.e. an undesirable increase in nutrients. Valuable native biotopes with species-rich habitats are being created here, providing a new home for many plants and animals.

In addition to the near-natural floodplain, ecologically valuable wet meadows and still water areas will also be created here. The water quality of the Bieber will also improve thanks to the stream's improved self-purification capacity. This will result in a high recreational value for the population.

In addition, the renaturation of the Bieber is an important building block for adapting to the damaging consequences of climate change. Firstly, it serves as flood prevention for the city of Offenbach. Additional important floodplains will be created outside the town. In the event of heavy rainfall, these will help to reduce the risk of flooding for the Bieber district. Secondly, the precious water is kept longer where it is needed by the ecosystem. This benefits, for example, the forest to the south of the village, which is better protected from drying out in dry summers.

The project is funded by the Hessian Ministry of Agriculture and the Environment, Viticulture, Forestry, Hunting and Homeland, with the City of Offenbach providing part of the funding.

The southernmost section, which runs through the nature reserve, is not accessible as there are no paths. After passing under the S-Bahn line in southern Erlensteg, it runs through species-rich meadows to Bremer Straße on the southern edge of the Bieber district. From here to Germaniastrasse, it disappears underground into a pipeline. On its way north, it flows in a straightened bed, then, after crossing under the B 448 federal highway, in a north-easterly direction. At the end, it leaves the city of Offenbach and flows into the Rodau near Mühlheim and then into the Main.

The water structure of the Bieber is "severely impaired" in the area of the city of Offenbach. In the upper reaches of the Bieber, the discharges from two sewage treatment plants in Dietzenbach and Heusenstamm have a negative impact on the water quality.

In addition, there are more than 20 rainwater overflows along the Bieber, which discharge untreated (waste) water from the sewage system directly into the Bieber during very heavy rainfall. Along a large part of the length of the watercourse, the Bieber is bordered, lowered, straightened, massively expanded and modified. As a result, the watercourse is unable to fulfill its ecological function. The limit values for total phosphorus, ortho-phosphate, ubiquitous pollutants (pollutants that occur everywhere due to human use) such as mercury and PAHs (polycyclic aromatic hydrocarbons), solid-bound and other pollutants are exceeded.