As population and development growth continue in Western Washington, stormwater poses an increasingly overwhelming challenge for regional practitioners, urban planners, and natural resource managers. This because stormwater from disparate sources is difficult to track as it collects and concentrates pollution (e.g., COCs associated with urbanization). Changing precipitation patterns increase the need for informed flooding and infrastructure protection planning. Though effective solutions exist, the billion-dollar question remains: how much stormwater intervention is needed and where to prioritize? Jurisdictions, utilities, and agencies spend significant public funds developing stormwater plans, leaving fewer resources for implementation. This is especially true for smaller Phase II jurisdictions without robust stormwater management departments. Through an expert-facilitated Design Thinking process, TNC learned about four major barriers to developing science-based management plans: (1) data layer acquisition; (2) slow and computationally intense hydrology modeling; (3) pollution-loading data too coarse to inform decisions; and (4) difficulty communicating with stakeholders, rate payers, and regional leaders by whom they are held accountable their planning choices. TNC partnered with Geosyntec Consultants LLC and Cheva Consulting, with input from UW EarthLab Climate Impacts Group (CIG), Washington Department of Fish & Wildlife, and NOAA Office of Coastal Management, to tackle these obstacles by mapping runoff and pollution loading at previously unattainable scales. The Stormwater Heatmap is a science-based tool designed to help stormwater practitioners tell stories using compelling visuals, reduce planning costs, and take targeted action on runoff and pollution hotspots by strategically siting infrastructure improvements. TNC launched V1.0 in March 2022 to increase the pace and scale of stormwater intervention projects so that people and nature can thrive.