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U.S. GEOLOGICAL SURVEY
Scientific Investigations Report 2007–5102

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Introduction

The Granger Drain and DR2 basins are located in the Yakima River basin in south central Washington (fig. 1). These agricultural basins are one of five areas in the United States selected for study as part of the National Water-Quality Assessment Program (NAWQA) Agricultural Chemicals: Source, Transport, and Fate Study (ACT). These basins are located in one of the most productive agricultural areas in the United States. As in many agricultural areas, crop production, pastures, and animal feeding operations in the Granger Drain and DR2 basins have been identified as sources of chemical contamination for surface and ground water in the area (Morace and McKenzie, 2002). To improve our understanding of how agricultural chemicals move through the environment and ways to best manage these chemicals, intensive chemical studies within the Granger Drain and DR2 basins were begun in 2001. Chemical samples were collected from all major hydrologic compartments within these basins, including the atmosphere, the subsurface unsaturated zone, ground water, overland flow, surface water, and the streambed surface-water/ground-water interface. This report details the environmental setting within Granger Drain and DR2 basins. The information presented here is intended for scientists and managers working in these and similar basins and provides a context in which to evaluate current and future work conducted as part of the NAWQA program in these basins.

Purpose and Scope

The purpose of this report is to present an overview of the current environmental setting of the Granger Drain and DR2 basins and identify factors influencing water quality in these basins. The environmental factors described here include the natural factors of physiography, geology, soils, hydrology, and climate, and the cultural factors of population and land use. This report largely represents a compilation of the results of selected water-quality studies and existing data with respect to the environmental factors in these basins. However, some new data are presented on land use and pesticide application rates.

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