Under the direction of EPA Office of Water Management, ECONorthwest is working with the City of Seattle to identify the environmental benefits associated with Green Stormwater Infrastructure (GSI) and to quantify its economic value. In the first stage of the project, ECONorthwest worked with Seattle Public Utilities to identify and describe the existing inventory of GSI. ECONorthwest used existing data along with local assumptions describing the extent to which different facilities manage stormwater runoff from adjacent surfaces to summarize the effects of the City’s GSI inventory in geographic terms. ECONorthwest also overlaid the inventory data on several socioeconomic variables (e.g., property values, ethnicity and race, household income) to show the distribution of the City’s GSI efforts relative to different segments of the City’s population.
In the second stage, ECONorthwest conducted a comprehensive review of existing and potential methods for quantifying the economic value of GSI-related benefits and prepared a memo summarizing dozens of benefit categories associated with GSI facilities. In the third stage, ECONorthwest worked with staff from Seattle Public Utilities to develop three build-out scenarios and summarized them geographically by basin type across the City.