Freshwater mussel: Ruhrverband steps up protective measures at the Bigge and Lister reservoirs

With the start of the summer holidays, the Ruhrverband is stepping up its information and awareness-raising measures to protect the Bigge and Lister reservoirs from the quagga mussel (Dreissena rostriformis bugensis). Whilst more extensive restrictions on use are already in place at the Hennetal Reservoir due to the particularly favourable conditions for the spread of the quagga mussel, the focus is now specifically on the two large reservoirs that have so far remained free of the quagga mussel.
To make leisure users even more aware of the necessary protective measures, the Ruhrverband will significantly expand the signage at the Bigge and Lister reservoirs in the coming weeks. In addition, large-format banners will be installed in heavily frequented areas to highlight the rules in force for the protection of our waters.

“With the Bigge and Lister reservoirs, we have two of the largest reservoirs in our catchment area that have so far been spared from the quagga mussel. This is a major success, but it is not a foregone conclusion. To ensure it stays that way, we rely on the cooperation of everyone who uses our reservoirs,” explains Prof. Dr Christoph Donner, Director of Technology and River Basin Management at the Ruhrverband.

Due to its water parameters – characterised by a high calcium content and sufficient nutrient levels – the Hennetal Reservoir is considered particularly vulnerable to initial colonisation. Consequently, stricter regulations for recreational use are already in place there. Although the conditions for the spread of invasive species are currently less favourable at the Bigge and Lister reservoirs, there is still a constant risk of introduction via boats, water sports equipment or fishing and diving gear.

The Ruhrverband therefore urgently appeals to all water sports enthusiasts, anglers, divers and other recreational users to consistently adhere to the existing protective measures: “Every single person can help ensure that the Bigge and Lister reservoirs remain free of the quagga mussel in future. Protecting our reservoirs is a task for society as a whole. Anyone using the waters should, of their own accord, do everything possible to preserve their unique function for nature, drinking water supply and leisure in the long term,” Donner continued.
At the heart of the protective measures is the so-called AHOI rule, which is mandatory for all boats:
 

• A – Empty: Remove all residual water completely.
• H – High-pressure cleaning: Clean the boat and trailer thoroughly, using hot water where possible.
• O – Optional disinfection: Treat hard-to-reach areas with three per cent hydrogen peroxide. Always check for material compatibility beforehand!
• I – Intensive drying: Allow the boat and trailer to dry completely for at least five days.

The same applies to stand-up paddleboards, kayaks, canoes, inflatable boats, and fishing and diving equipment: before using them on the Lister and Biggetalsperre reservoirs, clean them thoroughly, remove any water and allow them to dry completely before using the equipment in any other body of water. Ideally, you should use the equipment available from local hire stations.
The quagga mussel has been spreading across Europe for years and has already been detected in several reservoirs managed by the Ruhrverband. It causes lasting changes to aquatic ecosystems, deprives fish and other aquatic life of their food sources, and can cause considerable damage to technical installations and water management infrastructure. Preventing initial colonisation is therefore far more effective and cost-efficient than combating the problem at a later stage.

In addition to research and regular monitoring of the water bodies, the Ruhrverband continues to focus on public awareness campaigns and the active support of all visitors. Only by working together can we prevent the quagga mussel from becoming permanently established in the Bigge and Lister reservoirs.