More and more stormwater managers transparently manage their stormwater systems through web-based mapping tools. Here in Washington State, teams are putting together a Web Map that includes as many public facing stormwater system feature services as they can find. At the Washington State Department of Ecology, teams use web-based mapping tools to help manage their stormwater retrofit grant program. At the Department of Ecology, teams rely on public facing stormwater mapping data. The information they gather helps better understand the value of existing infrastructure to help guide retrofitting and maintenance priorities. Through simple overlay analysis, professionals can evaluate the relative stormwater management influence on receiving waters and/or groundwater. What teams learn informs coordination with internal and external partners. The web map is useful to the grant program and to many internal partners here at Ecology: NPDES MS4 permit managers, spill responders, TMDL permit managers, the Toxics Cleanup Program, and Shorelines Program. In this presentation, speakers will share how this effort has improved the understanding of municipal stormwater systems and the need for a more comprehensive dataset.