This page provides links to Healthy Watersheds Integrated Assessment reports, which are detailed technical documents that present the results of comparative measurement of a series of watershed health and vulnerability indices across large areas encompassing tens of thousands of watersheds. Several are statewide-scale efforts undertaken in partnership with state agencies and non-governmental organizations; others are targeted studies of specific ecological regions or river basins.  Statewide assessments have included California, Wisconsin, Alabama and Tennessee. Targeted assessments have included the Taunton River Basin, the Clinch River Basin, the Mobile Bay Watershed and the Montana Prairie Potholes Region. A Preliminary Healthy Watersheds Assessment covering the entire lower 48 states is in progress during 2015-2016.

Alabama and Mobile Bay Basin Integrated Assessment of Watershed Health (PDF) (50 pp, 12 MB)  The EPA Healthy Watersheds Program, Alabama Department of Environmental Management and Mobile Bay National Estuary Program conducted an integrated assessment of relative watershed health throughout Alabama and the Mobile Bay Basin. Twelve metrics were selected to describe landscape condition, hydrologic condition, habitat condition, geomorphology, water quality and biological condition. Metrics were quantified for each NHDPlus Version 2 catchment in Alabama and the Mobile Bay Basin using a combination of existing GIS layers and statistical models that predicted values of stream habitat condition, stream chemistry and stream biological condition metrics. Statistical models used landscape variables such as land cover, soil attributes and topography as predictors of stream conditions within each catchment. Metrics were combined into an overall Watershed Health Index and scores were mapped across Alabama and the Mobile Bay Basin to highlight priority areas for protection. In addition, an assessment of hydrologic connectivity to Mobile Bay was conducted for catchments in the Mobile Bay Basin using three metrics that described a catchment’s potential for water and material export and degree of downstream attenuation. Connectivity metrics were combined into a Mobile Bay Connectivity Index that can be used in conjunction with Watershed Health Index scores to identify portions of the Mobile Bay Basin that are both healthy and highly connected to Mobile Bay and are therefore priorities for maintaining natural water, sediment and nutrient inflows to Mobile Bay. To complement the analysis of watershed health and connectivity, four metrics describing the vulnerability of watersheds to future climate, land use and water use change were selected and quantified for NHDPlus catchments throughout the state and Basin. Vulnerability metrics were combined into a Watershed Vulnerability Index and index scores were mapped to further prioritize protection of watersheds that are healthy but vulnerable to future degradation.

California Integrated Assessment of Watershed Health (PDF) (118 pp, 9 MB) The EPA Healthy Watersheds Program and California’s Healthy Streams Partnership conducted an integrated assessment of relative watershed health throughout California. Six metrics describing structural watershed characteristics relevant to aquatic ecosystem health were quantified from GIS layers for each NHDPlus catchment in the state. An additional six stream condition metrics (chemical constituent concentrations, physical habitat index scores, etc.) were quantified for NHDPlus catchments in non-arid regions using statistical models. The models predicted values of stream health metrics based on a catchment’s land cover, soil attributes, topography and other landscape variables. Metrics were combined into a Watershed Condition Index and a Stream Health Index and scores across the state were mapped to highlight priority areas for protection. To complement the analysis of watershed health, eleven metrics describing the vulnerability of California watersheds to future climate, land use and water use change and wildfire risk were selected and quantified for NHDPlus catchments throughout the state. Vulnerability metrics were combined into a Watershed Vulnerability Index and index scores were mapped to further prioritize protection of watersheds that are healthy but vulnerable to future degradation.

Tennessee Integrated Assessment of Watershed Health (PDF) (105 pp, 8 MB)  This statewide assessment was carried out in partnership with the Tennessee Healthy Watershed Initiative (THWI), a collaboration of federal, state and nonprofit organizations committed to maintain and improve water resources in Tennessee watersheds. The Assessment identified relative health of watersheds across the entire state of Tennessee at the catchment (approx. 1-mile square) level, based on metrics characterizing Landscape Condition, Geomorphic Condition, Hydrologic Condition, Water Quality, Habitat Condition and Biological Condition. The scores from these six sub-indices were combined to create an overall Watershed Health Index.  Results can be presented for each metric, sub-index or Watershed Health or Vulnerability Index at multiple scales.  Geospatial datasets for all metrics and indices were delivered to the state and project partners along with an applications workshop at the project’s completion.

Wisconsin Integrated Assessment of Watershed Health (PDF) (111 pp, 10 MB)  The EPA Healthy Watersheds Program and the Wisconsin Department of Natural Resources (WDNR) conducted an integrated assessment of relative watershed health throughout Wisconsin. Fifteen metrics were selected to describe landscape condition, hydrologic condition, habitat condition, geomorphology, water quality, and biological condition. Metrics were quantified for each catchment in WDNR’s hydrography database using a combination of existing GIS layers and statistical models that predicted values of streamflow alteration, stream habitat condition, stream chemistry and stream biological condition metrics. Statistical models used landscape variables such as land cover, soil attributes and topography as predictors of stream conditions within each catchment. Metrics were combined into a Landscape Condition Index and an Aquatic Ecosystem Health Index. Index scores are being used for planning and evaluation of several WDNR watershed protection and restoration programs. To complement the analysis of watershed health, seven metrics describing the vulnerability of Wisconsin watersheds to future climate, land use and water use change were selected and quantified for catchments in WDNR’s hydrography database throughout the state. Vulnerability metrics were combined into a Watershed Vulnerability Index and index scores were mapped to further prioritize protection of watersheds that are healthy but vulnerable to future degradation.

Strengthening the Resilience of the Taunton River Watershed (PDF) (108 pp, 8 MB)  In partnership with EPA Region 1, The Nature Conservancy and local stakeholders, this project helped inform how Taunton communities decide on priority actions that would increase their overall resiliency and reduce their vulnerability to the converging impacts of climate change and development.  In addition to convening new networking opportunities among the Taunton River watershed stakeholders, the Taunton project also inventoried existing data and developed a decision making framework and a database tool. The tool for applying this framework is the focus of this report.  The framework links specific ecosystem services to important features of the watershed landscape to create an interactive tool that should help communities find ways to maintain the functions and processes most beneficial to their specific conditions (i.e., to become more resilient). The tool itself is designed so that stakeholders and decision makers can easily weight the ecosystem factors that are of most concern to them for the protection of the various ecosystem services.  It is also used to generate listings of top-ranked areas and export them for further examination, mapping and analysis. 

Clinch and Powell River System Integrated Assessment of Watershed Health (PDF)  (118 pp, 14 MB)  The Healthy Watersheds Program worked with the Clinch–Powell Clean Rivers Initiative (CPCRI) and others to identify healthy watersheds in the Clinch and Powell River System. The Clinch and Powell River System, upstream of Norris Lake, is one of the last free-flowing sections in the Tennessee River basin. It provides a habitat for many aquatic species, particularly rare freshwater mussels. The system begins in the mountains of southwest Virginia and empties into Norris Lake near Tazewell, TN, draining an area of 1.7 million acres. The Powell River begins in Wise County, VA, and flows 120 miles (190 km) southwest where it joins Norris Lake. The Clinch River begins in Tazewell County, VA, and flows approximately 200 miles (300 km) before reaching Norris Lake. The Clinch and Powell River System is home to one of the most diverse fish and mussel assemblages in North America, but over the years coal mining, agricultural activities and runoff from development have harmed this ecosystem. Despite these challenges, the watershed supports more than half of the native fish species currently in the Tennessee River basin, and at least 48 freshwater mussel species including 22 federally endangered species. The rivers also provide drinking water for more than 100,000 people, and are popular recreational sites. Healthy watersheds assessment methods and data products followed the conventional approaches from other assessments, producing watershed health and vulnerability indices and their respective subindices.

Montana Prairie Wetlands and Intermittent/Ephemeral Streams: Hydrologic Needs Assessment for Healthy Watersheds (PDF) (65 pp, 2 MB)  This project was conducted to address the hydrologic needs for healthy watersheds in Montana. Through a two-step process involving the development of hydrology–ecology hypotheses and a case study analysis of one of these hypotheses, it was demonstrated that precautionary limits of hydrologic alteration can be determined for the prairie wetlands of Montana. Twenty hydrology–ecology hypotheses addressing macroinvertebrates, fish, amphibians and birds were identified for individual- and landscape-level wetlands and intermittent/ephemeral steams. One of the hypotheses was then selected for a case study analysis to develop a proof-of-concept model relationship that describes hydrological alteration and ecological condition and supports the development of precautionary limits of hydrologic alteration.

Preliminary Healthy Watersheds Assessment for the 48 Conterminous United States: Project Summary (PDF) (2 pp, 0.3 MB)  This Preliminary Assessment will provide a “first cut” product nationwide at a small watershed scale with individual statewide summaries intended to help states and others without Healthy Watersheds Assessments engage in watershed protection planning and prioritizing. The integrated assessment approach involves scoring watersheds with indices of Watershed Health (landscape condition, habitat condition, hydrologic condition, geomorphic condition, biological condition and water quality) and Watershed Vulnerability (projected climate change, land use change and future water use). To the extent possible with nationally available data, the preliminary assessment follows the same approach.  In addition to statewide assessment, the preliminary assessment will score and compare each ecoregion’s watersheds and then re-summarize by each ecoregion portion within state boundaries. This will enable state-level users to consider watershed protection options relative to each ecoregion within their state as well as how top-ranked watersheds compare across the state as a whole.