Stacy D Jupiter , Aaron P. Jenkins , Joel Negin, Shylett Anthony , Ponipate Baleinamau, Rachel Devi, Sikeli Gavidi , Kini Koto Mailautoka, Sangeeta Mangubhai , Kelera Naivalu, Timoci Naivalulevu, Vilisi Naivalulevu, Nabeela Nasim , Sikeli Naucunivanua, Sarah Nelson, Ingrid Qauqau, Anaseini Ratu, Mereia Ravoka, Jacqueline Thomas , Andrew Tukana, Paul van Nimwegen , Ama Wakwella , Amelia Wenger , Donald Wilson, Pierre Horwitz 

Watersheds offer opportunities for place-based interventions to transform systems health via preventative versus reactive approaches to management that achieve multiple co-benefits for public and environmental health. The Watershed Interventions for Systems Health in Fiji (WISH Fiji) project embraced participatory knowledge co-production and action-oriented research to identify risks to public and ecosystem health, prioritize interventions to address risks, and monitor responses of the system to interventions. We used screening filters and local knowledge to collaboratively identify five watersheds for action with high prior incidence of water-related diseases (Fiji’s “three plagues” of leptospirosis, typhoid and dengue) and high risk to downstream environmental health. We reviewed literature to identify disease risk factors, evaluated overlaps with risks for downstream environmental impact, and designed 13 instruments to collect information about baseline risk. Following consultations to obtain free, prior and informed consent, we enrolled 311 households across 29 communities. We synthesized data to identify key risks at the household, community, and landscape level, which were communicated to community water and resource management committees and government leaders as part of developing water and sanitation safety plans for each community. Local committees identified 339 priority risk reduction actions across nine main categories: animal management; drainage; health systems surveillance; hygiene; integrated planning; land use management; sanitation systems; waste management; and water systems. As of October 2022, 154 interventions were implemented in the five watersheds across different risk categories and scales. While we can track changes to factors that reduce risk of water-related disease and improve environmental health, direct evaluation of impacts to public health is limited due to poor geolocation of case records. The WISH Fiji project is a model of cross-sectoral coordination that efficiently progresses multiple Sustainable Development Goals, but scaling requires sustained investment in interventions to realize full benefits, particularly for nature-based solutions that exhibit lagged responses.