In many ways, the Netherlands is the ultimate water country, yet water quality is increasingly under pressure. One of the most urgent threats to swimmable waters are harmful blue-green algal (or cyanobacterial) blooms and pathogenic bacteria in surface waters. These blooms are, especially in summer, a persistent and growing problem in Dutch lakes and waterways. They degrade water quality and pose serious risks to drinking water supplies and to recreational activities such as swimming.
In this edition of SustainaLab Talks, we will explore innovative strategies to prevent and control harmful blooms, examine the environmental factors that drive their occurrence, and address the pathogens and toxins present in these waters. We will also discuss the actions, collaborations and entrepreneurial initiatives needed to develop sustainable solutions and ecosystem services for communities, water managers and companies surrounding lakes and other recreational waters.
Join us for talks and a panel discussion on:
- The drivers of cyanobacterial and bacterial blooms
- Risks to swimming water quality, human health, ecosystems, and drinking water supplies
- Current and emerging strategies to prevent and control harmful blooms in recreational waters
- Key research gaps and urgently needed innovations
- Lessons that can be learned from management approaches in other countries
Speakers
- Frodo van Oostveen, CEO of World Waternet and board member of Amsterdam City Swim, will address the aspiration of swimmable cities from the perspective of urban water management. Building on his international water cycle experience in improving water quality and sanitation and his commitment to Amsterdam’s own swimmable canals and rivers, Frodo will explore what it takes to make and keep urban waters clean and safe for people to swim in—from governance and infrastructure to citizen engagement and (inter)national collaboration.
- Petra Visser, Associate Professor of Algal Ecophysiology at the University of Amsterdam’s Institute for Biodiversity and Ecosystem Dynamics, will explore the rapidly evolving science of harmful algal and cyanobacterial blooms. Drawing on her research into how these blooms develop, persist and produce toxins under changing environmental conditions, she will discuss new strategies to predict, prevent and control harmful blooms, and what this means for the future of freshwater ecosystems, water quality management and the safety of swimmable waters.
- Paul van der Wielen, Principal Scientist at KWR Water Research Institute and Professor in Microbial ecology of water systems at Radboud University, will take us into the microbial life of water systems. Drawing on his work on opportunistic pathogens such as Legionella, he will show how bacteria like E. coli and other microorganisms move through drinking water, cooling and wastewater systems, and how this relates to the safety of recreational and swimming water. He will also discuss how these microbes can be monitored and controlled, and how this knowledge helps secure safe, reliable water quality.
- Bob Brederveld, Aquatic Ecologist at Witteveen+Bos, will show how ecological knowledge can be put to work in real-world water management projects. Drawing on his experience with surface waters in urban and rural landscapes, he will discuss how hydrology, nutrient dynamics, sediments, and ecological processes influence water quality and ecological functioning. Through practical examples, he will demonstrate the value of integrated system analyses and ecological modelling in developing effective measures such as nature-based solutions and ecological design in creating healthier, more resilient aquatic ecosystems.
Moderation by Jef Huisman, Professor of Aquatic Microbial Ecology at the University of Amsterdam
Who should join?
This event is especially relevant for water managers and policy makers, professionals from drinking water companies and environmental consultancies, entrepreneurs and innovators in water and nature-based solutions, NGOs or community organisations focused on clean, swimmable (urban) waters and students and researchers in water, climate, ecology or public health.
Thursday, July 2nd 2026
15:30 – 18:00 (including networking drinks) 
SustainaLab, Matrix ONE, Amsterdam Science Park 301, 1098 XH Amsterdam
Language: English
Cost: Free