Strategic habitat restoration: Maximizing both ecological and social value in the Lower Duwamish River

The Lower Duwamish River (LDR) estuary is an 11-mile stretch of river that contains the core of industrial activity in the Seattle area. As Seattle's only river, it is also habitat for many of the region's valued fish species. Over 150 years of development have polluted and degraded the river, and significant habitat restoration is now required under federal and state law. However, given the context of urban development and industrial activity, projects tend to be small and opportunistic, with limited ecological value. At the same time, the LDR is home to several underserved urban neighborhoods, and restoration projects have the potential to bring significant social value to these communities. In order to resolve the diverse ecological and social goals for the LDR, this study analyzed 10 plans in order to develop a conceptual model of the value of restoration. Six ecological metrics and eight social metrics were identified from this model, and multi-criteria decision analysis was used to combine the metrics into overall indices of ecological and social value. These metrics and indices were then calculated for 511 waterfront parcels in the LDR. Results show more variability with positive skewness in the ecological index, and a more normal distribution with higher average values in the social index. Spatial analysis revealed higher ecological value in the northern, industrial section of the LDR, with particular dependence on the existing habitat network. Social value was higher in the southern section and as the river passes through residential neighborhoods. Both the methodology and results of this study can inform site selection for future restoration projects in the LDR, in support of the goal that such projects maximize both ecological and social value.