Grantee Research Project Results
Final Report: Estimating the Benefits of Stream Water Quality Improvements in Urbanizing Watersheds: An Ecological Production Function Approach
EPA Grant Number: R836165Title: Estimating the Benefits of Stream Water Quality Improvements in Urbanizing Watersheds: An Ecological Production Function Approach
Investigators: von Haefen, Roger , Taylor, Laura , Van Houtven, George L. , Obenour, Daniel Redd , Kenney, Melissa , Gerst, Michael
Institution: North Carolina State University , Desert Research Institute , University of Maryland - College Park
EPA Project Officer: Packard, Benjamin H
Project Period: June 1, 2016 through May 31, 2020 (Extended to May 31, 2021)
Project Amount: $799,728
RFA: Water Quality Benefits (2015) RFA Text | Recipients Lists
Research Category: Water
Objective:
To support EPA’s efforts to advance knowledge for conducting economic evaluations of environmental policies, the main objective of our proposed research is to develop and demonstrate methods for valuing the use and nonuse benefits of improving water quality in wadeable streams in urbanizing watersheds. These streams provide valuable ecosystem services and are subject to a combination of anthropogenic stressors that have led to pervasive degradation referred to as “urban stream syndrome.” Understanding how the general public perceives and values improvements in stream conditions is necessary to support EPA’s efforts to quantify the public’s willingness to pay (WTP) for water quality improvements.
Summary/Accomplishments (Outputs/Outcomes):
Our research efforts consisted of five main components: 1) a stated preference survey designed to elicit household’s willingness to pay to improve water quality in wadeable streams in urbanizing watersheds; 2) a series of focus groups and cognitive interviews designed to identify the most important ecological endpoints of wadeable streams and test alternative design features of our stated preference survey instrument; 3) a hierarchical water quality modeling framework that leverages existing sparse data for the Upper Neuse River Basin and can be used to forecast water quality indicators under alternative management scenarios; 4) an expert elicitation that links water quality indicators to the ecological endpoints identified in the focus groups; and 5) a case study of the Upper Neuse River Basin that illustrates how the afore mentioned components can be combined to generate policy-relevant benefit measures for alternative water quality improvement scenarios. Below we highlight our key findings from each of these research efforts.
Conclusions:
Stated Preference Survey: We developed and fielded a stated preference survey that elicited household’s willingness to pay for water quality improvements in wadeable streams in urbanizing watersheds. The survey instrument was developed over a five-year period by the research team with extensive input from focus groups, cognitive interviews, expert advice from Dr. Laura Taylor and Dr. Vic Adamowicz, and two pilot surveys. The survey employed a “push to internet” format whereby 12,500 randomly selected residents of the North Carolina counties of Wake, Mecklenburg and Guilford were invited by mail to participate in the online survey. 2,511 individuals ultimately completed at least one stated preference question (response rate = 21.4%), and several compehension checks and debriefing questions suggested the data was of high quality. Results from econometric modeling suggested that respondents value all thee ecological endpoints and are willing to pay roughly $16 to improve one stream mile from the lowest category to the highest category.
Water Quality Modeling: We used publicly available data for six water quality indicators to develop a predictive model that could be used to forecast water quality conditions in the Upper Neuse River Basin (UNRB) where data is often sparse in both temporal and spatial dimensions. The model uses an elegant hierarchical Bayesian approach that efficiently uses all available data and the linkages in water quality across time and space. Sparse data environments like the one found in our application are common in many policy settings, so the modeling framework employed here should be transferable to other applications.
Expert Elicitation: To link the output from the water quality model to the ecological endpoints that individuals care about, we used an expert elicitation. Eight experts participated, and their mappings from six water quality indicators to three ecological endpoints over 100 hypothetical scenarios allowed us to estimate ecological production functions that link measurable indicators to the three levels of ecological endpoints – ecosystem condition, human health risk, and murky water days – that the public cares about.
Upper Neuse River Basin Case Study: To illustrate how the various aspects of our research efforts can work in unison to inform policy, we developed a case study for the Upper Neuse River Basin. The case study leveraged predictions on how six water quality indicators are likely to change in response to interventions that reduce the negative impacts of streambank erosion, impervious cover, and random pollution sources such as leaking pipes. These changes in indicators are mapped into changes in ecological endpoints which are then fed into the water quality valuation model estimated with the stated preference survey data to generate monetary values for two hypothetical clean-up scenarios in two separate sub-watersheds in Wake County, North Carolina. The results suggest, for example, that the average Wake County household is willing to pay roughly $104 per year for the water quality improvements resulting from a 25 percent increase in canopy cover combined with a 25 percent decrease in the negative effects of impervious cover in the Crabtree and Walnut Creek sub-watersheds located in the densely-populated central part of Wake County. We found some evidence of distance decay in these values (i.e., residents living in close proximity to the cleaned-up watersheds elative to those living further away).
Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 2 publications | 2 publications in selected types | All 2 journal articles |
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Type | Citation | ||
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von Haefen R, Van Houtven G, Naumenkio A, Obenour D, Miller J, Kenney M, Gerst M, Waters H. Estimating the benefits of stream water quality improvements in urbanizing watersheds: An ecological production function approach. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 2023;120(18):e2120252120 |
R836165 (Final) |
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Supplemental Keywords:
Water quality, economic benefits, willingness to pay, stated preference methods, expert elicitation, ecological production function, wadeable streams, Upper Neuse River Basin.Relevant Websites:
NC State University - EPA Water Quality Grant Exit
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.
Project Research Results
- 2019 Progress Report
- 2018 Progress Report
- 2017 Progress Report
- 2016 Progress Report
- Original Abstract
2 journal articles for this project