To mitigate the harmful effects of stormwater runoff, many cities in the United States are constructing green stormwater infrastructure (GSI), yet the varied perceptions of GSI by local municipal managers can make or break the implementation of GSI in any given city. We conducted a series of focus groups with municipal managers from two adjacent regions in the Pacific Northwest (US) – Portland, Oregon and Clark County, Washington – where many of the earliest and most extensive applications of urban GSI have occurred. We aimed to understand the extent to which municipal managers fundamentally differ in their considerations of GSI, even within one metropolitan region. Results indicate that Portland respondents were optimistic about GSI implementation emphasizing stakeholder buy-in and regulatory systems. Alternatively, in Clark County, an unfunded state mandate, public concern, and uncertainties about facility performance culminated in a cautionary approach to GSI. The variation in findings has many implications for implementing GSI.