In this grade 4 interdisciplinary unit, students are instructed to consider water issues in the city of San Francisco (California). Using Internet and other resources, participants are required to prepare a detailed letter to a U.S. Congressional committee dealing with water issues, and possibly to testify before Congress. Students may represent groups, including people suffering from a water shortage, or conservationists opposed to a proposed dam. The student guide provides a list of resources, including Internet sites, and detailed instructions on how to complete the activity. The teacher's guide ties the unit to California state standards and gives suggestions on how to conduct and evaluate the unit. (RJC)