Dataset: Estimating biotic integrity to capture existence value of freshwater ecosystems

Estimating the value of changes in water quality requires the definition of biophysical features that link changes in ecosystems to changes in social systems. Those linking features must be interpretable to people and serve as effective ecological indicators. This work defines a linking feature that is appropriate for capturing existence values in a forthcoming national stated preference survey of Clean Water Act regulations. Further, we modeled and spatially predicted this feature to account for the dependence of survey respondents’ preference on baseline aquatic conditions near them. We outline steps to provide insights on the mechanisms that will aid in forecasting changes in the linking feature in responses to candidate policy options.

Impact/Purpose

The US Environmental Protection Agency (EPA) conducts economic analyses as one means to evaluate proposed regulations under the Clean Water Act. Current practice uses a Water Quality Index (WQI) to compare management scenarios to determine potential benefits and costs to society. However, a limitation of the existing WQI is that it focuses solely on human use values and fails to capture benefits that come from nonuse values. A range of research has shown that non-use values can be quite large, so quantifying them can be of critical importance to EPA decision making. In this paper, we describe research to identify an index of biological health (i.e., condition) to act as a companion to the WQI that can help the EPA estimate benefits associated with nonuse values. Using focus groups, we compared two indicators of biological condition that are commonly used by the EPA and states to assess the condition of streams and lakes. The selected indicator was found to be far more interpretable by focus group participants, which is critical to unbiased estimates of benefits. Previous work has shown that the willingness of the public to pay for (or accept) water quality regulations depends on current water quality near them. Interpolated values can help us refine our estimation of nonuse value by accounting for how biological condition varies regionally across the US. Therefore, we report on the development and application of preliminary models to interpolate values of this selected indicator to streams and lakes across the conterminous US. This work makes several contributions towards improving the accuracy and completeness of benefits estimation. First, to our knowledge, this is the first time that indicators of biological condition have been compared in a focus group setting. Our results provide insight into what makes an indicator of biological condition interpretable by the public and will improve forthcoming surveys of the public designed to measure their willingness to pay for improvements in water quality. The identification of an appropriate companion metric to the WQI is also a critical step to improving the completeness of benefits estimation since previous approaches did not account for nonuse values. Finally, this study will improve the way we value nonuse benefits by providing interpolated estimates of current biological condition near survey respondents. This research supports work being conducted in collaboration with economist in the EPA’s National Center for Environmental Economics.

Citation

Hill, R., Chris Moore, J. Doyle, S. Leibowitz, P. Ringold, AND B. Rashleigh. Dataset: Estimating biotic integrity to capture existence value of freshwater ecosystems. U.S. Environmental Protection Agency, Washington, DC, 2025. [DOI: 10.23719/1532239]

DOI: Dataset: Estimating biotic integrity to capture existence value of freshwater ecosystems