EPA”s National Stormwater Calculator is a desktop application that estimates the annual amount of rainwater and frequency of runoff from a specific site — any address in the United States — based on local soil conditions, land cover and historic rainfall records. The calculator accesses several national databases to provide local soil and weather conditions for the chosen site. Users, such as landscape architects, land developers or urban planners, supply information about the site”s land cover as well as what types of green infrastructure they would like to use. Green infrastructure can include low impact controls such as green roofs, rain gardens, rain barrels, and porous pavement that retain rainfall on site until it eventually evaporates into the air, infiltrates the ground, or is otherwise used.