Adequate supplies of water are essential to people, the economy and the environment. Yet the Nation faces an increasing set of water resource challenges. Aging infrastructure, rapid population growth, depletion of groundwater resources, impaired water quality associated with particular land uses and covers, reservoir sedimentation, water needed for human and environmental uses, increased domestic energy development, and climate variability and change all play a role in determining the amount of fresh water available at any given place and time. It is increasingly recognized that water is the primary means through which climate change impacts the earth and people’s livelihoods and well being. This book examines the Water SMART initiative, a program that recognizes the U.S. Department of Interior’s role in providing Federal leadership in the pursuit of sustainable water supply for people, the economy, and the environment.