In this wide-ranging keynote speech at Princetons She Roars conference, Environmental Protection Agency chief Lisa Jackson talks about the historic importance of womens leadership in efforts to safeguard the health of the planet.In a modern environment and a modern economy, clean air and clean water do not happen by accident, Jackson said. It takes vigilance and work to make sure those fundamental things are protected and passed on to the next generation.Jackson, who received her masters degree in chemical engineering from Princeton in 1986, is introduced by Emily Carter, director of Princetons Andlinger Center for Energy and the Environment.