Environmental planning is essential for climate action, as cities face air pollution, flooding, drought, and other environmental stresses. Yet research on these challenges remains limited in the state of Amazonas, Brazil. Building on a prior participatory study of 1,242 residents, this article advances a long-term research agenda focused on urban water management. The study pursues three goals: update, identify, and classify Benchmark Smart Sustainable Cities (BSSCs), with priority given to the Gold tier (GBSSCs); map ECO AI and Non-AI initiatives, AI techniques, and digital enablers used by GBSSCs to address urban water challenges (Manaus main concern); propose and disseminate Gate4EcoAI, an interactive platform with GBSSCs' urban water initiatives. This applied research triangulated ten international city rankings using a mixed-methods approach (systematic literature review, bibliometric and documentary analyses, statistical methods, open-science practices, and AI-assisted tools) to collect, clean, analyze, and visualize data. Of 265 cities assessed, 99 were classified as BSSCs (20 as Gold). GBSSCs applied 76 regulatory instruments and adopted at least 243 distinct initiatives to address water challenges. Gate4EcoAI is a multidimensional, queryable evidence-to-policy bridge, with valuable initiatives to support the development of roadmaps for urban water challenges. By linking proven initiative types (e.g., Network Process Control, Quality Monitoring), dominant AI techniques (ML-Anomaly Detection, Supervised ML), and enablers (IoT, Cloud) to real-world statuses, it empowers AI developers, policymakers, utilities, and researchers with evidence-based benchmarking to adapt the best practices locally. For Manaus and analog cities, this structured knowledge base bridges science-to-policy gaps, accelerating resilient water governance amid Amazonian vulnerabilities.