Water supply in the Southwestern United States depends on snow. Students discover its importance through analysis and evaluation of data, satellite images, space shuttle photos, and ground-based observations, and then apply their findings in a... (View More) role-play. Working in seven groups representing the states in the Colorado River watershed, students assume the roles of U.S. senators to propose and defend their stand on the allocation of Colorado River water by state and by usage. The URL opens to the investigation directory, with links to teacher and student materials, lesson extensions, resources, teaching tips, and assessment strategies. This is Investigation 4 of four found in the Grades 9-12 Module 1 of Mission Geography. The Mission Geography curriculum integrates data and images from NASA missions with the National Geography Standards. Each of the four investigations in Module 1, while related, can be done independently. (View Less)