Download Preliminary Healthy Watersheds Assessments
The EPA Healthy Watersheds Program developed Preliminary Healthy Watersheds Assessments (PHWA) in 2017 in support of states' and other partners' efforts to identify and protect high quality waters. EPA released an update to the PHWA in 2021.
The PHWA project is a set of 48 statewide and 85 ecoregional-scale assessments that score watershed health and vulnerability across the conterminous United States. The assessment was based on the Healthy Watersheds Assessment Framework, an analytical approach that focuses on six key attributes of watershed health: Landscape Condition, Geomorphology, Habitat, Water Quality, Hydrology, and Biological Condition. In addition to characterizing watershed health, the PHWA also includes estimates of relative watershed vulnerability, defined as the potential for future degradation of watershed processes and aquatic system health.
2021 Update to the PHWA
EPA included updated PHWA watershed health and vulnerability scores in Version 2.2 of the Watershed Index Online, released in August 2021. Updated 2021 PHWA scores are also available in state Recovery Potential Screening Tools.
Click here for an overview document that describes the 2021 update to PHWA, including a list of indicators that were updated since the original 2017 PHWA.
Click here for an Excel data file containing 2021 PHWA indicator definitions, metadata, and lists of specific indicators used in statewide and ecoregional assessments.
Original 2017 PHWA Data Downloads
All 2017 PHWA products are available as zipped, state-specific data packages below. Each state-specific, zipped package contains the following:
A cover memo introducing the PHWA, including state-specific summary statistics and a set of PHWA watershed health and watershed vulnerability maps;
An overview document that describes the PHWA project's purpose, methodology, data sources, and potential uses (available at https://www.epa.gov/hwp/examples-integrated-assessments-watershed-health#integrated);
An ArcGIS file geodatabase containing the PHWA Indicators, Sub-Indices and Indices of watershed health and vulnerability, compiled on the 12-digit hydrologic unit code (HUC12) scale;
A user-friendly Excel data file containing a full set of all watershed health and vulnerability scores and example maps;
An updated Recovery Potential Screening (RPS) Statewide Tool including all the PHWA scores along with many other watershed indicators. This flexible tool is used for comparing watersheds in terms of key factors affecting watershed condition (learn more at https://wwww.epa.gov/rps). RPS tools and user guides are currently the sole content of the Alaska, Hawaii and territorial data packages because the 2017 PHWA was limited to the conterminous 48 states.
You may need additional software to view some of the links on this page. See EPA’s Free Viewers and Readers page. The links will vary in file size.
Please contact EPA for information about PHWA development for HI, AK, territories and tribal lands.