Tracer Hydrology Practices, Challenges, and Opportunities Across Latin America and the Caribbean

Tracer hydrology in Latin America and the Caribbean has made significant progress in recent decades, largely through the sustained support of the International Atomic Energy Agency (IAEA). Current practises show water stable isotope applications and precipitation-groundwater monitoring at the core of most networks, providing valuable insights into recharge mechanisms, groundwater to surface water connectivity, pollution tracking, and climate variability. Despite these advances, critical challenges persist, including short and fragmented monitoring records, limited capture of extreme events, restricted data accessibility, and persistent barriers related to funding, analytical capacity, and weak policy integration. Improving science communication emerges as an urgent need to transform technical findings into actionable knowledge that informs decision-makers and empowers communities. Opportunities exist to build on IAEA's legacy by sustaining long-term networks, diversifying tracer applications, mobilising citizen science in monitoring efforts, expanding modelling and laboratory capacity, and advocating for FAIR data sharing across end-users. Strengthened collaboration across the region, improved communication, and deeper policy engagement can elevate tracer hydrology into a pillar of regional water governance and hydro-climate resilience. © 2026 The Author(s). Hydrological Processes published by John Wiley & Sons Ltd.