Estimates of ecological footprints generally account for waste assimilation requirements and are expressed as a measure of land area. Water footprints also account for water used to assimilate pollution, by considering the volume of dilution water required to maintain water quality standards (Hoekstra, 2008, in press). Ecological footprints describe the implications of regional or national consumption activities on natural resources and the environment by expressing those impacts in terms of the land area required to support the target population (Wackemagel and Rees, 1996; Wackemagel, et al., Thus ecological footprints enable one to compare the ecosystem implications of consumption activities across regions and countries, and to assess whether a region or country is consuming resources in a sustainable or unsustainable fashion, from a global perspective.