Nonpoint source pollution measures in the Clean Water Act have no detectable impact on decadal trends in nutrient concentrations in U.S. inland waters.
Nathan Tomczyk, Laura Naslund, Carolyn Cummins, Emily V Bell, Phillip Bumpers, Amy D Rosemond
Author Information
Nathan Tomczyk: Odum School of Ecology, University of Georgia, 140 E. Green St., Athens, GA, 30602, USA. nathan.tomczyk@gmail.com. ORCID
Laura Naslund: Odum School of Ecology, University of Georgia, 140 E. Green St., Athens, GA, 30602, USA.
Carolyn Cummins: Odum School of Ecology, University of Georgia, 140 E. Green St., Athens, GA, 30602, USA.
Emily V Bell: School of Public & International Affairs, University of Georgia, 415 Baldwin Hall, Athens, GA, 30602, USA.
Phillip Bumpers: Odum School of Ecology, University of Georgia, 140 E. Green St., Athens, GA, 30602, USA.
Amy D Rosemond: Odum School of Ecology, University of Georgia, 140 E. Green St., Athens, GA, 30602, USA.
The Clean Water Act (CWA) of 1972 regulates water quality in U.S. inland waters under a system of cooperative federalism in which states are delegated implementation and enforcement authority of CWA provisions by the U.S. Environmental Protection Agency. We leveraged heterogeneity in state implementation of the CWA to evaluate the efficacy of its nonpoint source provisions in reducing nutrient pollution, the leading cause of water quality impairment in U.S. inland waters. We used national survey data to estimate changes in nutrient concentrations over a decade and evaluated the effect of state-level policy implementation. We found no evidence to support an effect of (i) grant spending on nonpoint source pollution remediation, (ii) nutrient criteria development, or (iii) water quality monitoring intensity on 10-year trends in nutrient concentrations. These results suggest that the current federal policy paradigm for improving water quality is not creating desired outcomes.
