Estimating the benefits of stream water quality improvements in urbanizing watersheds

What is it about?

Streams in urbanizing watersheds are threatened by economic development that can lead to excessive sediment erosion and surface runoff. These anthropogenic stressors diminish valuable ecosystem services and result in pervasive degradation commonly referred to as “urban stream syndrome.” Understanding how the public perceives and values improvements in stream conditions is necessary to support efforts to quantify the economic benefits of water quality improvements. We develop an ecological-production framework that translates measurable indicators of stream water quality into ecological endpoints. Our interdisciplinary approach integrates a predictive hierarchical water quality model that is well suited for sparse data environments, an expert elicitation that translates measurable water quality indicators into ecological endpoints that focus group participants identified as most relevant, and a stated preference survey that elicits the public’s total willingness-to-pay for changes in these endpoints. To illustrate our methods, we develop an application to the Upper Neuse River watershed located in the rapidly developing Triangle region of North Carolina (USA). Our results suggest, for example, that residents are willing to pay roughly $127 per household and $54 million in aggregate (2021 US$) for water quality improvements resulting from a stylized intervention that increases stream bank canopy cover by 25% and decreases runoff from impervious surfaces, leading to improvements in water quality and ecological endpoints for local streams. Although the three components of our analysis are conducted with data from North Carolina, we discuss how our findings are generalizable to urban and urbanizing areas across the larger Piedmont ecoregion of the eastern US.

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Photo by Simon Caspersen on Unsplash

Photo by Simon Caspersen on Unsplash

Why is it important?

Federal, state, and local environmental agencies are often required by law and executive order to monetize to the maximum extent possible the benefits of new environmental regulations. Our interdisciplinary research fills a gap in the literature by quantifying the economic benefits of urban stream water quality improvements in the Southeastern Piedmont region of the United States.

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