Freshwater monitoring across the globe: the role of citizen science within the European Water Framework Directive (WFD) and the United Nations Sustainable Development Goals (SDGs), and opportunities to incentivize the collaboration with environmental regulators

Citizen science plays a crucial role in advancing the objectives of the European Union’s Water Framework Directive (WFD) and the UN’s Sustainable Development Goals (SDGs). Among the key strengths of citizen science is that it fills information gaps in the management and observation of aquatic ecosystems, especially small rivers that often lack national and sub-national agency monitoring. The present study explores opportunities and challenges of integrating citizen science data with those of Environmental Agencies. The current state of the art is discussed through a critical review of 47 publications concerning freshwater citizen science, focusing on data quality and geographical distribution. Examples of citizen science projects are also presented. Additionally, opportunities and challenges to increase the impact of freshwater citizen science are addressed by the authors.