The U.S. Geological Survey (USGS) is developing SPARROW models (SPAtially Related Regressions On Watershed Attributes) to assess the transport of contaminants (e.g., sediment and nutrients) through United States Pacific watersheds (the Columbia River basin; the coastal drainages of Washington, Oregon, and California; the Klamath River basin; the Central Valley of California, and the west slopes of the Sierra Nevada Mountains). SPARROW relates instream water quality measurements to spatially referenced characteristics of watersheds, including contaminant sources and factors influencing terrestrial and aquatic transport. A watershed property that is expected to influence sediment and nutrient delivery to streams is the area of potential livestock grazing land. The spatial data set "Potential Grazing Land Within the Pacific Drainages of the Western United States, 2011" represents areas that were suitable for livestock grazing (primarily cattle) in 2011. This data set was developed by considering relevant landscape attributes with regards to the potential for land to be suitable for livestock grazing. These attributes included land cover type, slope, proximity to water bodies and streams and designated grazing alottments.