Summer 2015

Progress on Nonpoint Pollution: Barriers & Opportunities

Adena R. Rissman and Stephen Russell Carpenter

Nonpoint source pollution is the runoff of pollutants (including soil and nutrients) from agricultural, urban, and other lands (as opposed to point source pollution, which comes directly from one outlet). Many efforts have been made to combat both types of pollution, so why are we making so little progress in improving water quality by reducing runoff of soil and nutrients into lakes and rivers? This essay examines the challenges inherent in: 1) producing science to predict and assess nonpoint management and policy effectiveness; and 2) using science for management and policy-making. Barriers to demonstrating causality include few experimental designs, different spatial scales for behaviors and measured outcomes, and lags between when policies are enacted and when their effects are seen. Primary obstacles to using science as evidence in nonpoint policy include disagreements about values and preferences, disputes over validity of assumptions, and institutional barriers to reconciling the supply and demand for science. We will illustrate some of these challenges and present possible solutions using examples from the Yahara Watershed in Wisconsin. Overcoming the barriers to nonpoint-pollution prevention may require policy-makers to gain a better understanding of existing scientific knowledge and act to protect public values in the face of remaining scientific uncertainty.

ADENA R. RISSMAN is an Assistant Professor of the Human Dimensions of Ecosystem Management in the Department of Forest and Wildlife Ecology at the University of Wisconsin–Madison. Her research has appeared in such journals as Conservation Letters, Journal of Environmental Management, Environmental Science and Policy, and Landscape and Urban Planning.

STEPHEN R. CARPENTER, a Fellow of the American Academy since 2006, is the Stephen Alfred Forbes Professor of Zoology and the Director of the Center for Limnology at the University of Wisconsin–Madison. He is the author of Princeton Guide to Ecology (with S. A. Levin et al., 2009) and Regime Shifts in Lake Ecosystems: Patterns and Variation (2003). His research has appeared in such journals as EcologySustainability, and Science.

Authors’ Note: We thank the Water Sustainability and Climate Team, which is funded by National Science Foundation DEB-1038759.

Water is an important, dwindling resource. Water and aquatic ecosystems support industry, agriculture, outdoor recreation, aesthetic pleasure, aquatic food sources, and livelihoods. Massive, expensive efforts have been made to improve water quality and “repair what has been impaired.”1 These efforts have led to some important gains, but water quality is still poor in many rivers, lakes, and coastal oceans. Runoff of soil, nutrients, and other chemicals from agricultural, urban, and other lands is called nonpoint source pollution. In contrast, point source pollution comes directly from a pipe, such as at an industrial or municipal facility. Runoff of phosphorus–also called nonpoint phosphorus pollution–is a major cause of toxic algae blooms, oxygen depletion, and fish kills in streams, lakes, and reservoirs.2 Why are we not making progress on nonpoint source pollution in water quality? What are the challenges of producing science to predict and assess nonpoint management and policy effectiveness, and of using this science in management and political decisions? Finally, what changes are needed to improve water quality? .  .  .


  • 1Charles J. Vörösmarty, Michel Meybeck, and Chistopher L. Pastore, “Impair-then-Repair: A Brief History & Global-Scale Hypothesis Regarding Human-Water Interactions in the Anthropocene” Dædalus 144 (3) (2015): 94–109.
  • 2Stephen R. Carpenter, Nina F. Caraco, David L. Correll, Robert W. Howarth, Andrew N. Sharpley, and Val H. Smith, “Nonpoint Pollution of Surface Waters with Phosphorus and Nitrogen,” Ecological Applications 8 (3) (1998): 559–568.
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