This study will identify the nation's highest-priority water science and resource challenges over the next 25 years; summarize the current water science and research portfolio of the USGS Water Mission Area (including primary roles and responsibilities, range and balance of scientific and technical expertise; collaborations with other federal agencies, state and local government agencies, academic institutions, non-governmental organizations, and the private sector); and provide recommendations on the strategic water science and research opportunities for the Water Mission Area that would address the highest-priority national water challenges and would have high potential to benefit USGS strategic science priorities.