A coalition of environmental groups is launching a fundraising drive to restore part of the overtaxed Colorado River that has become more desert than delta.

Conservationists from Mexico and the U.S., including actor Robert Redford, will gather Saturday at the Arizona Science Center in Phoenix for a "low-water-use" gala.

Redford will give remarks as well as screen "Watershed," a documentary on the river system produced by Redford and his son Jamie Redford.

The director of the Colorado River Campaign, Gary Wockner, says there's an opportunity to restore the river delta, which lies in Mexico and once had 2 million acres of wetlands.

Looming shortages are predicted on the river serving some 40 million people in California, Arizona, Colorado, Nevada, Utah, New Mexico and Wyoming. Mexico also has a stake.