"100 Wild Streams for Hesse" - State of Hesse supports renaturation of the Hainbach stream

The Hainbach flows from Gravenbruch between Tempelsee and Lauterborn through Offenbach. From the Spessartring, its path leads it through a canal into the Main. The course of the stream was straightened many years ago and built over in the city. This restricts important habitats for animals and plants. The city of Offenbach am Main now wants to change this. "We want to preserve the ecologically valuable floodplain forest sites and restore some of them. With the help of the state, we have the opportunity to redesign a section of the Hainbach in a near-natural way," says Mayor and Head of Climate Protection Sabine Groß, commenting on the successful application for the "100 Wild Streams for Hesse" program by the Office for the Environment, Energy and Climate Protection.

The Hainbach is now one of 100 streams in Hesse that are being renaturalized as a model. As a support service, the state of Hesse is providing the municipalities with a service provider, Hessische Landgesellschaft mbH, which will support them from the first planning step through to the implementation of the renaturation measure. In addition, the costs will be subsidized by the state with a funding rate of up to 95 percent in accordance with the "Guideline for the Promotion of Measures for Water Development and Flood Protection".

Project manager Christina Beyer from the Office for the Environment, Energy and Climate Protection is delighted about the inclusion of the Hainbach in the funding program: "With the support of the Hessische Landgesellschaft, the project is making good progress and it is becoming realistic to achieve the goal we have set ourselves: to renaturalize almost two kilometers of the Hainbach in the upper reaches of the city forest over the next three years." With this renaturation measure, the city of Offenbach is fulfilling its obligation to restore its rivers and streams to a good ecological status by 2027 in accordance with the European Water Framework Directive. The main aim is to preserve or restore typical aquatic habitats and promote biodiversity associated with water.

Around 35% of the total length of the Hainbach has been heavily modified, piped or built over. At the end of 2019, the Hainbach and seven other watercourses in Hesse were designated as "heavily modified". "In built-up urban areas, it is not possible to improve the structure of the watercourse and restore human interventions at a reasonable cost," explains Heike Hollerbach, Head of the Office for the Environment, Energy and Climate Protection. This applies in particular to long and completely piped sections of watercourse. "In the upper reaches of the watercourse and in the remaining floodplain areas, structural improvements can provide ecologically valuable habitats for animals and plants and, above all, relevant functions for flood protection."

According to the EU Water Framework Directive, the planning area is located on a 1.7-kilometre section of the watercourse (river kilometers 3.4 to 5.1) in the city forest south of the Stadthalle. The structural measure starts at the so-called "Nasses Dreieck" parking lot and runs past the grounds of the Arbeiterwohlfahrt Kreisverband Offenbach am Main - Stadt e.V. (AWO) to Müllerweg.

"A structural improvement to the waterway can only be achieved if the surrounding area is also considered. For example, the landscape conservation area between Waldstraße, Dreiherrnsteinweg, Schäferbornweg and the AWO grounds is part of a superordinate urban biotope network. According to the current landscape plan, there is a priority need for action to preserve the ecologically valuable area and improve its value. The renaturation in this section makes a major contribution and helps the city of Offenbach to create important retention areas in the event of flooding by connecting the watercourse to the existing old course structures and slope seepage sources," emphasizes Heike Hollerbach.

Alexander Jeschke, Deputy Head of Office and Head of Division for the Lower Water Authority, points out that the renaturation is also a further building block on Offenbach's path to becoming a sponge city: "The widening of the watercourse bed and (re)creation of meanders (a curved watercourse bed) creates larger retention areas and longer water retention times in the area. This also helps in part against flooding and thus contributes to cooling through increased evaporation and is therefore also a measure for adapting to climate change."

The Office for the Environment, Energy and Climate Protection is planning a workshop in the second half of the year. At this workshop, interested citizens can contribute their ideas for the renaturation of the Hainbach.

Note on an editorial change, June 1, 2:30 p.m.: Spessartring changed in the second sentence. Originally Sprendlinger Landstraße was stated.