Effectiveness of local regulations on nonpoint source pollution: Evidence from Wisconsin dairy farms

Although the Clean Water Act's regulation of point source pollution has had a significant effect on water quality, nonpoint sources of pollution, especially animal agriculture, remain a leading unevenly regulated source of water pollution in the United States. This work studies the effectiveness of local manure management regulations on dairy farms in Wisconsin. Wisconsin represents a unique policy experiment in the delegation of nonpoint agricultural pollution policy in a state with economically important small, nonpoint, dairy farms. Using hand collected regulatory data from Wisconsin counties we estimate the effects of changes in local regulations on water quality outcomes. The results demonstrate that a few easily implemented and verifiable regulations such as nutrient management plans have significant short-term effects on water quality, whereas other less observable and difficult to implement regulations have no discernible effects in the short term. The work points to a number of potential policy levers to improve the Management of nonpoint pollution, as well as the challenges of nonpoint source regulatory policies on slow-moving hydrologic processes.