Perennial grass has been proposed as a potential candidate for producing cellulosic biofuel because of its promising productivity and benefits to water quality, and because it is a non-food feedstock. While extensive research focuses on selecting and developing species and conversion technologies, the impact of grass-based biofuel production on water resources remains less clear. As feedstock growth requires water and the type of water consumed may vary considerably from region to region, water use must be characterized with spatial resolution and on a fuel production basis. This report summarizes a study that assesses the impact of biofuel production on water resource use and water quality at county, state, and regional scales by developing a water footprint of biofuel produced from switchgrass and Miscanthus � giganteus via biochemical conversion.