The Mother Nature Network has just published their list of the ten greenest cities in the United States . There is as yet no official criteria set by the EPA for determining a city’s “greeness,” MNN considered key areas to measure the effectiveness of a municipality’s efforts at carbon footprint reduction, including air and water quality, efficient recylcling and management of waste, percentage of LEED certified buildings, acres of land devoted to green space, use of renewable energy, and eas