Four East Valley cities might finally see a return on multimillion-dollar investments in Roosevelt Dam as Arizona’s wet winter promises to further raise water levels in the lake.

Scottsdale, Mesa, Chandler and Tempe could gain some extra insurance against longterm drought if this abnormally rainy, snowy season turns out to be only an interruption of an extended dry climatic cycle.

More than a decade ago, the cities pitched in 40 percent of a $45 million local contribution to help fortify Roosevelt Dam and raise it to 357 feet from 280 feet. In return, the cities were granted rights to water that reaches a specified 15-foot portion of the additional elevation of the dam.

The $430 million dam modification — funded also through several federal, state and Maricopa County agencies — was completed in 1996, the year Arizona entered its latest drought. The reservoir has never filled to the level where the cities would own the water.

Roosevelt Lake has to be 81 percent full for that to happen. The water level dropped to just 10 percent of the reservoir’s capacity during the record dry year of 2002, but returned to 30 percent a year ago and by Thursday, thanks to the five recent wet months, had reached 80 percent, according to Salt River Project, which manages the reservoir and dam.

It’s likely that this week’s rains will push Roosevelt’s waters even higher, and if runoff from the high-country snowpack remains as strong as expected it’s a sure bet that by spring, water will fill the entire area of dam elevation allotted to the cities, said Dallas Reigle, SRP senior hydrologist.

That will provide the municipalities more than 286,000 acre-feet of water. One acre-foot is roughly enough to meet the typical water needs of a family of four for a year.

“We’re really hoping this happens. We’ve been waiting for 10 years,” said Roger Manning, director of the Arizona Municipal Water Users Association.

It was through the association that the four East Valley cities formed a consortium with Phoenix and Glendale to invest in the dam improvement. Phoenix paid 50 percent of the contribution, Mesa 15 percent, Scottsdale, Chandler and Glendale 10 percent each and Tempe 5 percent. Each gets a commensurate share of whatever amount of water rises above the designated dam elevation.

“We’re pretty happy about this. . . It will be a little windfall for our water supply,” said Kathryn Sorensen, Mesa’s water resources coordinator.

Sorensen and water officials in Tempe, Scottsdale, Chandler and Phoenix said their cities are unlikely to use the water any time soon since they have enough in storage to handle near-term needs. It can be banked indefinitely even if continued drought brings water levels in Roosevelt Lake back down to recent lows.

That’s how the deal pays off most, said Tom Gallier, water resources director for Tempe, which gets about 90 percent of its supply from Salt River Project.

“The long-term value of this is going to prove itself. . . . This is water that could tide us over in future years, because all the prognosticators are saying this (wet season) is only a blip in a very long drought cycle. We may not see another winter like this for 10 years,” Gallier said.

Even if the water were to be used immediately, individual customers would not see a noticeable impact in terms of water rates — other than helping to keep them from rising.

The cities still would have to put the water through a full range of treatments and quality testing to meet health and environmental standards. Expenses for the processes account for the largest percentage of water service costs to customers, Sorensen said.

There is an additional benefit when the cities take delivery of the water. Under the consortium’s deal, the municipalities are to be compensated for the value of whatever power is produced by their water allotment as it is released from Roosevelt Lake and run through SRP’s hydroelectric generating station at Roosevelt Dam.

SRP power official Mike Clester said if the cities had their full allotments moved through the system it could collectively net them “into the hundreds of thousands of dollars.”

Roosevelt Dam timeline

1898: Site chosen for a dam originally to be called the Tonto Basin Dam at a location in Salt River the early Arizona pioneers called “The Crossing,” where American Indians, farmers and ranchers forded the river at a narrow gorge a short distance below the confluence of the Salt River and Tonto Creek, 76 miles northeast of Phoenix.

1902: President Theodore Roosevelt helps win approval of the Federal Reclamation Act, paving the way to for the dam — one of the world’s highest masonry dams — to later be named for him.

1905-1911: 280-foot high dam is built. Cost: $10.3 million. Roosevelt attends dedication March 11, 1911.

August 1952: Roosevelt Lake runs dry during a severe multi-year drought.

October 1990: Roosevelt Lake bridge completed, taking traffic off the top of the dam.

Jan. 20, 1993: Dam reaches all-time high water elevation at 2,139 feet above sea level. Salt River Project expects new record this year with a projected strong snowpack runoff in spring.

April 1996: Construction completed on $430 million modification of the dam, raising it to 357 feet as part of a project to serve the Valley’s growing water needs and increase the structure’s strength. Actual construction took about five years — using enough concrete to pave a two-lane road from Phoenix to Tucson.

Sept. 1, 2002: In Arizona’s driest year on record, water in Roosevelt Lake falls to it lowest level in the recent drought years, at 2,034 feet above sea level, only 10 percent of the lake’s capacity. Lake would have again run dry without reserves of Colorado River water from the Central Arizona Project reaching the Valley by then.

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