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METHODOLOGY FOR EVALUATING THE EFFECTIVENESS OF NONPOINT SOURCE POLLUTION ABATEMENT PROGRAMS
Citation:
NEAL, J. R., JOEL J. ALLEN, J. A. GOODRICH, E. HOBBINS, R. SHAMBLEN, AND M. PIRNIE. METHODOLOGY FOR EVALUATING THE EFFECTIVENESS OF NONPOINT SOURCE POLLUTION ABATEMENT PROGRAMS. Presented at Nonpoint Source Conference, Indianapolis, IN, November 28 - 30, 2006.
Impact/Purpose:
To inform the public
Description:
The Upper Big Walnut Creek watershed encompasses 190 square miles of predominantly agricultural cropland (65%) in Central Ohio (USA) where agronomic fertilizers and herbicides are used in row crop production. Runoff from the watershed drain to Hoover Reservoir which is Central Ohio’s largest source of drinking water; providing water to more than 750,000 people. The City of Columbus’ long-term water quality monitoring program of the reservoir (1981 to present) has detected occurrences of elevated levels of the agricultural herbicide atrazine above the maximum contaminant level (MCL) for drinking water. In response, Columbus developed a multi-barrier approach to attain compliance with the atrazine MCL. Columbus installed a $4.5 million powdered activated carbon (PAC) feed facility to chemically remove atrazine. However, PAC treatment costs can exceed $1.5 million annually. To complement this treatment technology, Columbus initiated a partnership with the agricultural community to identify and implement best management practices (BMPs) that reduce atrazine and other non-point source pollutant runoff. Since in 1999, the US Department of Agriculture’s Environmental Quality Incentives Program (EQIP), through the local conservation offices, has provided more than $2 million for field-level best management practices (BMPs) on more than 40,000 cropland acres. Yet, critical questions remain about the program’s performance and effectiveness at attaining water quality goals that reduce treatment costs for Columbus. The USDA’s National Agricultural Pesticide Risk Analysis (NAPRA) model was selected to quantify and characterize atrazine runoff from each of the watershed’s 3,096 crop fields. NAPRA was used to quantify field-scale annualized mass (load) atrazine runoff and, generate comparative risk analysis graphs among BMP scenarios for each soil type within a crop field. Historical environmental landscape, climatic land agronomic management and BMP scenarios were derived from actual field-level data obtained from USDA Natural Resources Conservation Service (NRCS) and Farm Services Agency (FSA) field offices. NAPRA model output data were incorporated in a GIS for mapping purposes that identified locations of high atrazine runoff risk. Initial findings indicate that the nonpoint source pollution abatement program does reduce atrazine runoff into the city’s water supply. Results of this project will provide a national methodology demonstrating how watershed organizations can characterize water quality concerns, select appropriate BMPs and evaluate the effectiveness of restoration efforts at the field and watershed scales. This methodology can be applied to source water protection, storm water and total maximum daily load programs.