GROWTH AND DEVELOPMENT in twenty-first century America imposeincreasing stress on natural systems, which in turn increases conflicts among the diverse users of these systems. Problems among water users are evident even in states like Florida with abundant rainfall: declining water levels and saltwater intrusion in wells, polluted and diminished flows in springs and rivers, collapse of sinkholes, dried marshes, disappearing lakes, red tides, and habitat destruction, and other problems documented in the case studies in this volume. Scientific study of natural ecosystems is increasing our awareness and understanding of these problems and of possible solutions, but even advanced ecological knowledge has limited power to help resolve conflicts among competing demands for resources.