PALM SPRINGS, Calif. -

Two major California water organizations expressed support today for a pair of local agencies that have been sued for water rights by a local Indian tribe.

The Association of California Water Agencies and the Southern California Water Committee are backing the Desert Water Agency and the Coachella Valley Water District, who were sued in May by the Agua Caliente Band of Cahuilla Indians.

The suit, filed in U.S. District Court in Riverside, asks a judge to declare the tribe's rights to valley groundwater and prevent the Desert Water Agency and Coachella Valley Water District from overdrawing and ``degrading'' the local water supply. The suit seeks a legal ruling on the tribe's ``prior and paramount reserved right to sufficient water underlying the Coachella Valley.''

The Association of California Water Agencies -- considered the largest statewide group of public water agencies in the country -- sent a letter of support to the local agencies, stating that the lawsuit ``creates dangerous uncertainty for the residents and businesses of the region and does not advance any public good.''

``Further, we worry that such a lawsuit could create a dangerous precedent of moving toward adversarial relationships between tribes and local water districts, when cooperative management of California's water resources best serves the entire population of California, including the tribal members,'' the letter stated.

The Southern California Water Committee -- which includes businesses, government representatives, agricultural groups, labor unions, environmental groups and water agencies -- sent a letter to Agua Caliente tribal Chairman Jeff L. Grubbe, asking the tribe to end its lawsuit ``to protect the best interests of the public and the Coachella Valley as a whole.''

The letter stated that the lawsuit creates uncertainty about ``future water supply reliability, potential increases in customer rates and impacts to the region's recovery'' and asked the tribe to work with the two agencies through the Integrated Regional Water Management Plan ``to chart the future for the region's water supply.''

In legal responses to the lawsuit, both agencies deny the tribe's ``aboriginal rights to the surface water and groundwater resources'' in the valley and have asked the tribe to drop the suit.

Grubbe said previously the tribe was asking the federal court to declare the tribe's water rights to ``prevent the Desert Water Agency and the Coachella Valley Water District from continuing to overdraft the aquifer and degrade the quality of existing groundwater,'' adding that independent investigations have shown that local water is being depleted and polluted.

``Since at least the 1990s, the Agua Caliente and others have aggressively urged the CVWD and DWA to take action to end the mismanagement, overdrafting and polluting of the aquifer underlying the Coachella Valley,'' Grubbe alleged in an earlier statement. ``The tribe has patiently attempted to work with CVWD and DWA to address these longstanding concerns, but to no avail.''

No hearings have been scheduled in the case, according to court records.