This story reports on possible restrictions on outdoor water use in Arizona if the Colorado River's flow continues to decline as expected this year. University of Arizona law professor Robert Glennon, a water policy expert, believes Phoenix and other cities should push conservation, whether by mandate or by rebate, and should consider paying people to trade in water-guzzling fixtures. "Water conservation remains the low-hanging fruit," Glennon said. "There are a lot of things we can do. Las Vegas has led the way."