Submitted to: Journal of Soil and Water Conservation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 22, 2011
Publication Date: November 30, 2012
Repository URL: http://handle.nal.usda.gov/10113/56361
Citation: King, K.W., Fausey, N.R., Dunn, R., Smiley, P.C., Sohngen, B. 2012. Response of reservoir atrazine concentrations following regulatory and management changes. Journal of Soil and Water Conservation. 67(5):416-423. Interpretive Summary: Atrazine is a cost-effective and proven herbicide for corn production in the US. However, atrazine concentrations in surface water frequently exceed drinking water standards. Agricultural programs, such as the Environmental Quality Incentive Program provide incentives to farmers to adopt conservation practices such as pesticide management. However, quantitative information on the effectiveness of these practices is often limited. This study quantifies the effectiveness of the practice at a watershed scale. Significant differences in reservoir atrazine concentrations were measured between three distinct time periods: pre atrazine label restrictions, post label restrictions, and EQIP implementation. The benefits of the practice greatly outweighed the costs of implementing the practices suggesting that watershed scale implementation of conservation practices is a cost effective approach for addressing nonpoint source pollution.
Technical Abstract: Since the early 1990s, atrazine concentrations in United States drinking water supplies exceeding the drinking water standard of 3 parts per billion (ppb) have been identified as a costly and major water quality concern. Atrazine levels in Columbus, Ohio tap water reached 8.74 ppb in the early 1990s, leading to a watershed approach aimed to reduce elevated atrazine concentrations. In 1999, the Environmental Quality Incentive Program (EQIP) was implemented in the watershed that feeds Hoover Reservoir, the primary drinking water supply for Columbus, Ohio. Through EQIP, the Natural Resource Conservation Service (NRCS) offered financial incentives to farmers and operators in an effort to reduce atrazine concentrations in the reservoir and maintain the concentrations below the drinking water standard. Monthly reservoir atrazine concentrations were measured from 1985 through 2005, representing three distinct time periods: no label restrictions (1985-1992); post label restrictions (1993-1998); and EQIP implementation (1999-2005). Significant (P<0.05) reductions in mean monthly reservoir atrazine concentrations were noted between all three time periods: no label restrictions (2.27 ppb) > post label restrictions (1.99 ppb) > EQIP implementation (1.18 ppb). No significant differences (P>0.05) were measured in precipitation or amount of corn planted between the three time periods. Additionally, for every dollar spent on conservation through the EQIP program, a $3.61 benefit for the City of Columbus was realized through savings for drinking water treatment to remove atrazine. For farmers and operators, atrazine is an economically viable and effective herbicide for crop production. This study indicates that annually eliminating application on approximately 16% of the crop production acres can reduce and maintain reservoir atrazine concentrations below drinking water thresholds. Thus, the findings from this study suggest that in the absence of EQIP, adding a second year of soybeans, a small grain, or a forage crop to the corn-soybean rotation even with atrazine application on corn should assist with maintaining reservoir atrazine concentrations below the drinking water standard.