Currently, electric power generation is one of largest water withdrawal and use sectors in the U.S. On the other hand, water distribution, treatment, and transmission is one of the largest energy use sectors. As future demands for energy and water continue to increase, competition for water between the energy, domestic, agricultural, and industrial sectors, could significantly impact the reliability and security of future energy production and electric power generation. To address these growing concerns, Congress directed the Department of Energy (DOE) to assess current and emerging national issues associated with the interdependencies between energy and water. As part of these efforts, DOE initiated the development a National Energy-Water Science and Technology Roadmap. The purpose of the Roadmap is to establish a longrange research, development, and demonstration program to support the efficient use of water and energy resources and sustainable and cost-effective future energy production and electric power generation in the U.S. To support these efforts, representatives from the DOE national laboratories, the Electric Power Research Institute (EPRI), and the Utton Transboundary Resources Center of the University of New Mexico School of Law, helped assess emerging energy-water interdependencies and support the Roadmap efforts. This paper provides a short overview of some of the emerging energy-water issues and summarizes the major Roadmap efforts to assess regional and national technical issues and needs associated with the interdependencies of energy and water. The Roadmap process was needs driven and a major element was the use of three needs assessment workshops – East, Central and West Regions - to review regional water and energy use trends and identify emerging major energy and water needs and issues. The workshops were held from November 2005 through January 2006 and included regional and national energy and water experts, representatives from national, state, tribal, and local governments, universities, private industry, and non-government organizations to solicit input on suggested improvements or changes in energy and water technology application, natural resource management, and natural resource use policies that could be implemented to ensure future energy supplies are reliable, secure, and sustainable.