National Watershed Characterization - 1999
Source: Environmental Protection Agency - Index of Watershed Indicators
Map Description:
The Index of Watershed Indicators characterizes the condition and vulnerability of aquatic systems in each of the watersheds in the United States. This involves an assessment of condition, vulnerability, and data sufficiency. The approach is simple. First, indicators of the condition of the watershed are scored and assigned to one of three categories: better water quality, water quality with less serious problems, and water quality with more serious problems. Second, indicators of vulnerability are scored to create two characterizations of vulnerability: high and low. The information provided by the Index of Watershed Indicators will help focus the attention of water quality managers and decision makers on areas with problems in need of restoration, on areas with good water quality in need of protection, and on areas where additional data is needed.

Cautions for this Product:
When looking at the results of the IWI, however, it is important to note that the strength of monitoring programs varies across the country. Areas with strong monitoring programs may show more problems than those with weaker programs. Good monitoring provides valuable environmental information and should be rewarded.

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