Those tribes, whose combined population falls short of 80,000, will control more than 1 million acre-feet of water per year.

That's enough to serve the residential needs of more than 5 million people, or roughly the entire population of Arizona.

That water is virtually all that remains for future growth in urban Phoenix and Tucson.

Cities whose supplies begin to run low in years to come will have to consider leasing water from the tribes at premium prices, if the tribes will part with it at all.

So far, some have.

The tiny Ak-Chin Indian Community provides all the water for Del Webb's Anthem development north of the Phoenix metro area, and the Salt River Pima-Maricopa Indian Community has signed leases with Phoenix and Scottsdale, the two cities most in need of new long-term water sources.

Other tribes have their own plans.

Gila River leaders say they'll use almost all the water from their settlement, 653,500 acre-feet, or enough to serve about 3 million people, to nurture long-fallow farming operations on their reservation.

Only about 41,000 acre-feet will be available for urban leases, at prices as high as $1,200 to $1,500 an acre-foot, compared to the base cost of $105 per acre-foot for cities that buy water from the Central Arizona Project.

An acre-foot is about 326,000 gallons, or enough water to serve a family of five for a year.

The tribes' claim on so much water remains in dispute among many in Arizona, especially agricultural users who stand to lose the most when the final allocations are made.

But cities and other agencies who have participated in the talks say settling the claims is far safer for the state than allowing a series of court cases to continue.

"Their claim extends to just about the entire basin," John Sullivan, associate general manager for the Salt River Project water group, told The Arizona Republic. "It would be more than the annual flow of the Gila River. The settlement really does eliminate the risk."

Settling the case won't resolve water allocations immediately. Once the tribes sign off, the agreement goes to Congress along with other issues related to the Central Arizona Project, the 336-mile pipeline that delivers water from the Colorado River to Phoenix and Tucson.

Arizona Sen. Jon Kyl, who is credited with keeping the discussions on track the past few years, hopes to introduce legislation this year, though most people involved with the talks say final approval could be two years or more away.

Arizona's Legislature also must sign off on some parts of the deal and unrelated claims by other tribes could complicate matters.

Some Navajo Nation leaders said last week that they want to reopen talks over as much as 2 million acre-feet of Colorado River water they believe they are owed.