While air quality regulations are the most salient set of environmental protection activities, the majority of government and industry pollution control expenditures are targeted toward protecting and improving water quality (CBO 1988; see also chapter 1). The politics behind air quality regulations were systematically and quantitatively evaluated in chapter 5. The current chapter extends this line of investigation into the area of water quality regulation. In this discussion, special emphasis will be placed on the differences in regulating water quality versus air quality. The politics surrounding each set of regulations is quite different, due in large part to their respective federal enabling legislation. These differences lead us to a different set of expectations when analyzing water quality regulations in the states.