The Colorado River, the Southwest's troubled lifeblood, tops an environmental group's endangered-rivers list for the third time in 23 years.

American Rivers' announcement late Tuesday marks the seventh time since 1991 that the Colorado made the group's top 10 list of endangered rivers.

The Colorado's repeated appearance stems from the perennial threats to the overallocated river, said Matt Niemerski, the group's Western water policy director. The newest No. 1 ranking traces to the ongoing drought and a recent Bureau of Reclamation study warning that the river's supply could fall 3.2 million to 8 million acre-feet short of the region's needs because of population growth and climate change, American Rivers said. An acre-foot provides a year's supply for two to three families.

"While there have been small steps made over the years with respect to water conservation and efficiency at the local level, the Bureau of Reclamation's study clearly points out that current trends are not sustainable," Niemerski said. He said a basinwide approach to water supply management, backed by robust federal and state financing, are needed to put the river on the path to recovery. "If we do not begin the process of planning for the future and get more progressive about how we will manage water in the basin, the Colorado River will eventually break."

The bureau, which operates the river's seven-state reservoir system, didn't respond to requests for comment on the endangered ranking. Tom McCann, an assistant general manager for the Central Arizona Project, which supplies river water to Phoenix and Tucson, disagreed with the ranking, although he agreed it's time for the region to act. Efforts to take such action are underway, he said.

"There will be work groups forming to explore water conservation and river augmentation" because of the bureau study, McCann said. He noted that despite a 13-year drought, the river's reservoir system remains about half-full. "That's not bad."

He said he found it interesting that while the river was No. 1 on the endangered list this year, it wasn't in the top 10 last year. The only changes on the river since then have been positive, he said. They include an agreement allowing Mexico to store its water in Lake Mead and authorizing release of some river water to the parched Colorado River Delta. The bureau's study was positive, he said, in that it called for better planning for river supplies and demand, and developed about 150 ideas toward that goal.

Amy Kober, American Rivers' spokeswoman, said the group likes to change its listings every year to highlight different rivers in trouble.

Val Little, director of the Water Conservation Alliance of Southern Arizona, said she's not surprised by the No. 1 ranking, since river runoff has been below normal 10 of the past 14 years.

Little predicted that a wide range of solutions for the river's problems will need to be tried. "Everything's got to be considered - conservation, reuse and new supplies."

Contact reporter Tony Davis at or 806-7746.