US EPA

This draft report investigates the issues and challenges associated with identifying, calculating, and mapping indicators of the relative vulnerability of water quality and aquatic ecosystems, across the United States, to the potential impacts of global change. Using a large set of environmental indicators drawn from the scientific and management literature, this draft report explores the conceptual and practical challenges associated with using such indicators to assess how the resilience of ecosystems and human systems may vary as a function of existing stresses and maladaptations.

This draft report investigates the issues and challenges associated with identifying, calculating, and mapping indicators of the relative vulnerability of water quality and aquatic ecosystems, across the United States, to the potential adverse impacts of external forces such as long-term climate and land-use change. The draft does not directly evaluate the potential impacts of global change on ecosystems and watersheds. Rather, it explores the implications of the assumption that a systematic evaluation of the impacts of existing stressors will be a key input to any comprehensive global change vulnerability assessment, as the impacts of global change will be expressed via (perhaps complex) interactions with such stressors. This is an assumption with an impressive pedigree, but, to date, there has been relatively little exploration of the practical challenges associated with assessing how the resilience of ecosystems and human systems in the face of global change may vary as a function of existing stresses and maladaptations. The work described in this draft report is a preliminary attempt at such an exploration.

This draft report takes as its starting point more than 600 indicators of water quality and aquatic ecosystem condition, along with numerous datasets from EPA, other federal agencies, and other organizations, as a testbed for identifying challenges and best practices (as well as gaps in ideas, methods, data, and tools) for calculating and mapping vulnerability nationally. Specifically:

• Challenges associated with identifying those indicators that speak specifically to “vulnerability” as opposed to those reflecting simply a state or condition;
• Challenges associated with calculating and estimating the values of these vulnerability indicators, including establishing important indicator thresholds that reflect abrupt or large changes in the vulnerability of water quality or aquatic ecosystems;
• Challenges associated with mapping these vulnerability indicators nationally, including data availability and spatial aggregation of the data;
• Challenges associated with combining and compositing indicators and developing multi-indicator indices of vulnerability.

This draft report is intended to be one building block for future work on multi-stressor global change vulnerability assessments. It is hoped that it will contribute to improved links between the decision support needs of the water quality and aquatic ecosystem management communities and the priorities and capabilities of the global change science data and modeling communities.

This draft report investigates the issues and challenges associated with identifying, calculating, and mapping indicators of the relative vulnerability of water quality and aquatic ecosystems, across the United States, to the potential adverse impacts of external forces such as long-term climate and land-use change.

Following external peer review and public comment, NCEA will consider all reviews and comments received in developing a final version of the report which will be released publicly and available for download from the NCEA Global Change Assessment website.

U.S. EPA. Aquatic Ecosystems, Water Quality, and Global Change: Challenges of conducting Multi-Stressor Vulnerability Assessments (External Review Draft). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-11/011A, 2011.

Comments on the assessment may be submitted and reviewed using the e-Government Regulations.gov Web site. From the site, select “Environmental Protection Agency” and the keyword “EPA-HQ-ORD-2011-0187" (for the docket ID) to comment on this report.