The Ruhrverband, the City of Essen, Weisse Flotte Baldeney and IG Baldeney are holding a consultation on the current situation regarding aquatic plants at Lake Baldeney

At the invitation of the Ruhrverband, representatives from the City of Essen, the Weiße Flotte Baldeney and IG Baldeney met for a joint expert conference on the current development of submerged macrophytes in Lake Baldeney. The background to this is the currently very pronounced growth of aquatic plants in the lake, which is leading to significant restrictions on water sports. The

consultations were prompted by the rescheduling of the German Junior and Age-Group Rowing Championships, which were originally scheduled to take place at Lake Baldeney from 25 to 28 June 2026 but have now had to be moved to Lake Elfrath in Krefeld due to the growth of aquatic vegetation. 

The conference focused on the latest scientific findings, an assessment of the ecological situation, and operational issues relating to water management and mowing strategy.

The meeting was opened by Markus Rüdel, press spokesperson for the Ruhrverband, who provided a detailed overview of the current situation at Lake Baldeney. The underwater vegetation in large parts of the lake is currently dominated by water milfoil. Waterweed (Elodea nuttallii), which has caused problems more frequently in recent years, is now only found sporadically. Despite the reduced presence of Elodea, the current developments are posing new challenges for water management. In particular, the morphological characteristics of pondweed are causing considerable technical difficulties during mowing operations, as the cuttings become severely entangled and place significantly greater strain on the mowing boats’ transport and conveyor systems. 

Dr Christina Meinert-Berning, Head of the Microbiology & Still Waters Group at the Ruhrverband and EGLV joint laboratory, added her perspective from a biological standpoint. She highlighted the conflict of objectives between the ecological benefits of macrophyte populations and the requirements of recreational use. Macrophytes are central components of a stable standing water ecosystem; at the same time, high biomass levels give rise to pronounced conflicts of use, particularly in performance-oriented water sports. Dr Klaus van de Weyer from

the company lanaplan presented an in-depth scientific assessment. He is a aquatic ecologist and a consultant and expert on aquatic and marsh plants, and attributed the exceptional growth of the vegetation to a combination of favourable environmental conditions in 2026. A prolonged spell of fine weather with high temperatures, low outflows and low mineral turbidity is said to have led to increased light availability. This effect was reportedly exacerbated by low chlorophyll concentrations and a pronounced clear-water phase in the spring. These conditions had created optimal growing conditions for submerged aquatic plants.

The currently dominant pondweed, a hybrid of Potamogeton crispus and Potamogeton friesii, is also highly competitive and can form massive stands under favourable conditions. Why this species, accounting for over ninety per cent of the population, has prevailed over the previously dominant waterweed has not yet been conclusively explained by science. Due to the presence of a hybrid water milfoil, which has not yet been described in the literature, it would be unreliable to make predictions about the further course of growth this year or even for the 2027 water sports season. 

Steffen Quast, Deputy Head of the Reservoirs Operations Centre at the Ruhrverband, reported on the operational mowing programme. In principle, the pondweed can be mown. The operational adjustments, in particular slower travel speeds and optimised conveyor technology, have proved their worth. Cooperation with the City of Essen is working very well; the existing infrastructure, comprising two mowing boats and a mobile unloading point, is largely utilised to full capacity. 

At the same time, however, water milfoil is significantly more challenging to manage than the previously dominant waterweed. It leads to increased maintenance requirements and greater strain on the mowing boat technology. Overall, whilst the situation remains manageable, logistical and staffing capacities are almost fully utilised. Plans are in place to optimise the mowing strategy in future, including through airborne monitoring, satellite-based detection of macrophytes and data-driven early-warning systems. 

During the discussions, the dynamics following mowing operations were also addressed. Boris Orlowski from the Weisse Flotte Baldeney pointed out that significant regrowth of vegetation becomes apparent within a few days of mowing. 

Hans-Walter Fink from IG Baldeney emphasised, from the perspective of the water sports clubs, the considerable disruption to training and competition activities on Lake Baldeney. He made a strong appeal to all parties involved to shape the framework conditions in such a way that both international and national competitions, as well as recreational sport, remain possible at the Essen site. 

In his subsequent assessment, Ruhrverband Chairman Prof. Dr Christoph Donner made it clear that Lake Baldeney, as an aquatic ecosystem, is subject to complex ecological dynamics. Interventions, such as sediment removal or redistribution, must be assessed very critically in the light of potential ecological risks, as they could destabilise the existing system in the long term. Furthermore, the sediment removal at Lake Harkort in 2001 showed that this cannot prevent the growth of aquatic plants. Increased mowing operations could only realistically be implemented if the local water sports clubs contributed financially. He referred to the broader developments in reservoirs and dams, which are increasingly shaped by climate change, invasive species and the return of native species. These changes are leading to new conflicts of use between water sports, leisure activities, nature conservation and water management functions. In future, he said, it would be necessary to move away from a reactive approach to problem-solving towards a strategic management of ecological transformations that systematically reconciles differing interests. 

In conclusion, Simone Raskob, Head of Division 6 (Environment, Transport and Sport) for the City of Essen, emphasised the need for a viable short-term strategy to safeguard upcoming major sporting events. 

Further biological surveys, including dives in July 2026, are already planned. All parties involved expressed their willingness to engage in close and ongoing dialogue. The conference took place in a constructive atmosphere and underlines the close cooperation between the Ruhrverband, the City of Essen and the water sports stakeholders at Lake Baldeney.