POLLUTION LOCATOR|EPA WATERSHED EVALUATION CATEGORIES

EPA's Index of Watershed Indicators (IWI) characterizes the condition and vulnerability of aquatic systems in each of the 2,262 watersheds in the 50 states and Puerto Rico. The Index evaluates water quality conditions, vulnerability, and data sufficiency. Extensive professional judgement is then used to integrate water quality indicators and watershed vulnerability indicators into an overall watershed health indicator. EPA assigns each watershed to one of seven watershed health categories:

Better Water Quality - Low Vulnerability:
Designated uses are largely met and other indicators of watershed condition show few problems. Pollutants or other stressors are low, so there is a lower potential for future declines in aquatic health. Actions to prevent declines in aquatic conditions in these watersheds are appropriate, but at a lower priority than in watersheds with higher vulnerability.

Better Water Quality - High Vulnerability:
Designated uses are largely met and other indicators of watershed condition show few problems. Significant pollution and other stressors exist, so there is a higher vulnerability to declines in aquatic health. These watersheds have the greatest need for actions to protect quality and prevent decline.

Less Serious Water Quality Problems - Low Vulnerability:
Watersheds with aquatic conditions below water quality goals and with problems revealed by other indicators. Pollutants or other stressors are low, so there is a lower potential for future declines in aquatic health. Actions to prevent declines in aquatic conditions in these watersheds are appropriate, but at a lower priority than in watersheds with higher vulnerability.

Less Serious Water Quality Problems - High Vulnerability:
Watersheds with aquatic conditions below water quality goals and with problems revealed by other indicators. Significant pollution and other stressors exist, so there is a higher vulnerability to declines in aquatic health. These watersheds have the greatest need for actions to protect quality and prevent decline.

More Serious Water Quality Problems - Low Vulnerability:
Watersheds with aquatic conditions well below water quality goals and with serious problems exposed by other indicators. Pollutants or other stressors are low, so there is a lower potential for future declines in aquatic health. Actions to prevent declines in aquatic conditions in these watersheds are appropriate, but at a lower priority than in watersheds with higher vulnerability.

More Serious Water Quality Problems - High Vulnerability:
Watersheds with aquatic conditions well below water quality goals and with serious problems exposed by other indicators. Significant pollution and other stressors exist, so there is a higher vulnerability to declines in aquatic health. These watersheds have the greatest need for actions to protect quality and prevent decline.

Insufficient Data:
There are insufficient data to accurately characterize the watersheds.