OneAquaHealth Policy Brief

Urban Stream Ecosystem Health as a One Health Priority

Urban freshwater ecosystems are essential for biodiversity, climate resilience, and public health, yet they are among the most degraded natural systems in European cities. The OneAquaHealth project assessed 100 urban stream sites across five European cities and found consistent evidence that urbanization severely compromises freshwater ecosystem health and increases risks for human well‑being. As highlighted in the Policy Brief, “urban freshwater ecosystem restoration should be prioritized as a preventive One Health measure.”

Urbanization is driving widespread ecosystem degradation

Across all study cities, urban pressures – such as nutrient pollution, pharmaceutical contamination, channel modification, soil sealing, artificial light at night, and loss of riparian vegetation – significantly reduced biodiversity and ecosystem resilience. Pharmaceuticals were detected in 91% of monitored sites, and diatom deformities emerged as early‑warning indicators of contamination that standard monitoring would not detect.

Degraded streams increase public health risks

The findings reveal a strong link between ecological decline and human health outcomes. Poorer stream conditions were associated with higher cause‑specific mortality and reduced life expectancy, reflecting the loss of ecosystem services such as water purification, climate regulation, and mental health benefits. Urban streams also hosted Diptera species capable of transmitting West Nile virus, dengue, and chikungunya, while degraded habitats reduced natural insect predators such as birds, amphibians, and fish.

Biofilms in more urbanized streams carried clinically relevant pathogens and high loads of antibiotic resistance genes, underscoring the public health implications of freshwater degradation.

Restoration is a powerful preventive health strategy

The Policy Brief calls for urban freshwater restoration to be recognized as a public health investment. Measures such as riparian vegetation recovery, channel renaturalization, improved sewage treatment, and reduced artificial light can simultaneously enhance biodiversity, reduce disease risks, and strengthen climate resilience.

Tools to support evidence‑based decision‑making

OneAquaHealth provides several practical tools to help cities act:

• Decision Support System (DSS): Guides users from ecosystem assessment to tailored restoration measures.

• Toolkit of Solutions: A comprehensive catalogue of nature‑based and structural interventions for urban stream rehabilitation.

• City Dashboards & GEOSSIP: Interactive platforms integrating ecological, environmental, and satellite data for site‑specific insights.

• Citizen Science App: Enables residents to contribute observations, expanding monitoring capacity and public engagement.

Policy recommendations for Europe

The Policy Brief urges policymakers to:

• Integrate urban freshwater restoration into public health planning.

• Expand the Water Framework Directive to include One Health indicators linking ecosystem and human health.

• Strengthen multilevel governance and integrated data systems across environmental, water, urban planning, and health sectors.

Author(s): Janine P da Silva, Sónia RQ Serra, Ana R Calapez, Dirk S. Schmeller, Ângela Freitas, Carina Dantas, Marie Anne Eurie Forio, Harm op den Akker, Silje Havrevold Henni, Maria João Feio (2026) OneAquaHealth Policy Brief. Urban stream ecosystem health as a One Health priority. Horizon Europe: OneAquaHealth project. European Union. pp. 11 [project DOI: https://doi.org/10.3030/101086521].