These drainage basin boundaries are used to characterize stream sites in the current and future development of Watershed Regression for Pesticides (WARP) models (Stone and Gilliom, 2009; Stone and others, 2008; Larson and others, 2004). PURPOSE REFERENCES: Stone, W.W. and Gilliom, R.J., 2009, Update of watershed regressions for pesticides (WARP) for predicting atrazine concentration in streams: U.S. Geological Survey Open-File Report 2009-1122, 22 p., accessed March 9, 2010, at https://pubs.usgs.gov/of/2009/1122/ Stone, W.W., Gilliom, R.J., and Crawford, C.G., 2008, Watershed regressions for pesticides (WARP) for predicting annual maximum and maximum moving-average concentrations of atrazine in streams: U.S. Geological Survey Open-File Report 08-1186, 19 p., accessed March 9, 2010, at https://pubs.usgs.gov/of/2008/1186/ Larson, S.J., Crawford, C.G., and Gilliom, R.J., 2004, Development and application of watershed regressions for pesticides (WARP) for estimating atrazine concentration distributions in streams: U.S. Geological Survey Water-Resources Investigations Report 03-4047, 68 p., accessed March 9, 2010, at https://pubs.usgs.gov/wri/wri034047/
