This casebook provides a strong doctrinal base that spans eastern and western water resource issues, as well as groundwater and surface water. This edition retains its in-depth consideration of water institutions and federal-state and interstate water relations; and it contains sharpened coverage of property rights claims. It includes major new Supreme Court decisions, along with new key cases from several jurisdictions. It reflects the emergence of water law as a leading edge of legal adaptation to changing climate, considering impacts on water availability and the demands for its use.