A growing body of research shows that healthy watersheds are a vital component of a well-functioning water supply infrastructure system. WRI’s Green-Gray Assessment (GGA) method allows stakeholders to value the costs and benefits of integrating green or natural infrastructure into water supply systems to improve performance. Building on the GGA’s latest applications in Latin America, this paper overviews the GGA’s three preassessment steps and six main steps, and provides recommendations on how to present results.