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What is the overall condition?
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The ReVA approach permits one to look across the entire region and, in a glance, see the overall pattern of environmental quality. The regional information can be summarized in a number of different ways and
the simplest methods are used to provide an overview (all variables are equally weighted).
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The regional pattern indicates that environmental quality is lowest in urban areas with few natural resources, such as extensive natural forests, and many stressors, such as air and water pollution. The highest environmental quality is associated with less populated areas such as southern West Virginia and north central Pennsylvania. These areas have more natural resources and fewer stressors. The two methods are in reasonable agreement in the overall spatial pattern. However, the maps differ in a number of details such as the environmental condition of watersheds in the vicinity of Raleigh, North Carolina. The greatest confidence can be placed in areas where the two maps agree.
The simple methods used here give a general overview of environmental conditions in the region. But the maps only provide a relative ranking of the watersheds, that is, which watersheds are in better or worse condition. There is no objective standard to which all the watersheds can be compared. Thus, the best watershed may not be objectively satisfactory and the worst watershed may not be objectively problematic. Therefore, the maps can only provide a general impression of where environmental problems are likely to be greatest.
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