pH of rainfall in the USA, 2002

The pH of precipitation, and water bodies, vary widely across the United States. Natural and human processes determine the pH of water. The National Atmospheric Deposition Program has developed maps showing pH patterns, such as the one below showing the spatial pattern of the pH of precipitation at field sites for 2002.

Note this map shows one point in time, and since 2002 there has been a general reduction in things that cause acid rain. A newer map might look very different than this one. Still, lower precipitation pH values still will occur in the northeastern U.S.