In Palm Springs, one of the hottest regions in California, precious groundwater has been depleted for decades to build lush golf courses, swimming pools and tract homes. Now the local American Indian tribe is pressing for a right to help manage that water.The Agua Caliente Band of Cahuilla Indians, which owns two casinos in the popular desert tourism region, has been buying water for decades from the two government water agencies that manage local groundwater, the Desert Water Agency and the Coachella Valley Water District.