WATERBODY CLASSIFICATION AND LAND COVER PATTERNS AS PREDICTORS OF WATER QUALITY

Many states classify waterbodies according to groups of designated uses, suggesting that classifications are correlated with water quality. The primary assessments of water quality do not consider classification, so this assumption is untested. Additionally, water quality has been shown to be influenced by land use; however, land use is not typically part of waterbody classification systems. To determine the relationships among water body classification, water quality, land cover, and forest fragmentation, we analyzed existing water quality data for the State of Connecticut from the United States Geological Survey and the Connecticut Department of Energy and Environmental Protection and land cover data from the National Land Cover Dataset. Connecticut uses a unique classification system that includes separation of drinking water sources (Class AA) and waterbodies receiving waste water discharges (Class B). Compared with Class AA waters, Class B waters tend to have higher levels of nitrogen, solids, some ions (chloride and sodium), and certain metals (copper and lead). Class B watersheds have less forest cover, more development and more impervious cover than Class AA watersheds. We identified a subset of Class B waterbodies with “Class AA-like” water quality. These Class B waterbodies have upstream land cover that is “AA-like” and less forest fragmentation than either Class AA or the bulk of Class B watersheds. We found that water quality is more strongly correlated with land use and forest fragmentation parameters than with water body classification, suggesting that incorporating land cover into classification systems would result in classes that more closely reflect water quality.