Lake Roosevelt has hit record high levels to the delight of Rim boaters and fishermen and to the relief of Valley water users, although inflows are already declining steadily.
The six Verde and Salt river reservoirs Salt River Project operates all shimmer at nearly 100 percent capacity -- 2.2 million acre feet of water snatched under the glower of an intermittent 14-year drought.
The same reservoirs stood at about 11 percent capacity several years ago and about 64 percent one year ago. But a succession of storms between December and February produced the fourth wettest three-month period in 108 years of record keeping. Although the drought appeared to reassert itself in the form of the fifth driest March on record, the the rains stopped abruptly in March, runoff boosted Roosevelt to 98 percent capacity. All told, the winter's rain was about 120 percent of normal.
The inflow this week has dropped to about 2,500 cubic feet per second from 2,700 last week and should taper off gradually as the snow in the high country melts away.
The rush of water into Lake Roosevelt will give the Valley a fresh cushion against continued drought -- and should give Rim Country residents easy access to perhaps the best bass fishing in the country.
"I think that what it means for this year is that we can breath a collective sigh of relief," said Charlie Ester, manager of water resource operations for the Salt River Project. "But in the long run, you have to look at where we live: Drought is the norm."
Although the three sodden winter months put enough water in the reservoirs to tide the Valley through another two to four years of drought, the current water deficit remains one of the eight worst in the past 600 years. Even more worrisome, the years 2006 and 2002 were the two lowest rainfall years in Rim Country in the past 600 years, according to studies of the growth rings of trees.
"Is that an indication of potential climate change or just variability that just happened to throw the two bad years together?" said Ester. "Either way, I'd certainly not recommend that anyone plant grass because Roosevelt Lake is full."
It might, however, be a good year to buy a bass boat.
The wet winter comes at an historic moment -- just when the addition of 77 feet to the height of the dam has increased the storage capacity of the lake by about 272,000 acre feet -- enough extra water to supply about 140 towns the size of Payson.
Dam managers mostly funded the higher dam to provide flood control. Various studies revealed the Salt River watershed could generate much larger floods than dam designers originally thought. Six valley cities contributed to the cost of the $340 million dam raising project to secure rights to the extra water.
That higher dam means that with the record lake levels, great tracts of formerly dry, desert land is now underwater. Cottonwoods and willows can stand the inundation, but desert plants will likely die. As a result, the rising lake levels have drowned tamarisk and mesquite and other plants that had created a rich riparian habitat at the inlets to the lake -- like along lower Tonto Creek.
The federal government required SRP to offset the drowned riparian habitat used by endangered species like the Willow Flycatcher by buying and restoring three times as much riparian habitat on the Verde, Gila and San Pedro Rivers.
But the loss to the birds and other wildlife dependent on the riparian areas will be the gain of the bass and other fish in the reservoir, since the drowned plants will provide lots of cover and nutrients. As a result, Lake Roosevelt fish should enjoy the "new lake" effect, with a peak in productivity for bass, catfish, crappie and other fish.
"Lake Roosevelt is supposed to be the best bass fishing reservoir in the United States -- if not the world -- for the next year," said Ester.
Roosevelt should drop 15 feet by the end of the summer, Ester predicted. This rise and fall of water levels based mostly on the demand for water far down stream generally keeps plants from getting a foothold along the shoreline, making reservoirs good for fish but much worse for other wildlife than natural lakes or streams.
Currently, Roosevelt is one foot short of completely full and still rising at about an inch a day. However, the level at which the lake is declared "full" is fairly arbitrary -- since there's still 63 feet worth of height on the dam to accommodate floods. If the lake ever rose to anywhere near the top of the new dam, it would submerge the highway and most of the communities around the shoreline.
Currently, SRP is releasing about 1,152 cubic feet per second from Roosevelt -- about half of the inflow. Dam managers want to release the water to which the six Valley cities are entitled from Roosevelt, while leaving the much smaller Verde River reservoirs holding SRP's water as full as possible.
Currently, Bartlett and Horseshoe reservoirs on the Verde hold their full, 286,057-acre-foot capacity. Roosevelt alone holds 1,628,220 acre feet.
At the peak of the runoff, SRP was letting 12,000 cubic feet per second past the Verde Reservoirs and 23,000 feet per second at Granite Reef Dam, below where the Salt and Verde join. That was the first time SRP has released excess water from Roosevelt since completing the dam expansion in 2007. All told, SRP released a total of about 150,000 acre feet of excess water for the season.
The brimming reservoirs allowed SRP to dramatically cut its use of groundwater -- down to 75,000 acre feet from the 275,000 acre feet in the previous year.
Rain and snow on the Colorado River watershed this winter have also cushioned the effects of the long drought just. The storms that graced the Rim Country also delivered 120 percent of the normal snowpack in the Rocky Mountains.
However, that provides just a little breathing space on the Colorado River system, which supplies a third of the state's water.
Despite the relatively wet winter, both Lake Mead and Lake Powell remain about half full. Hydrologists expect the shrunken Lake Powell to rise by about 50 feet this spring. All SRP's reservoirs on the Salt and Verde rivers combined hold about 10 percent as much water as Lake Mead alone.
Ironically, the water experts had predicted things would be much worse at this point. Arizona was supposed to suffer a long, dry winter this year, thanks to a drop in water temperatures in the Pacific Ocean that began in the middle of 2007.
Normally, this "La Nina" condition produces dry winters and drought in the southwest. The strongest La Nina in 35 years was supposed to steer storms to the North, leaving Arizona dry. Instead, the state got four major winter storms.
All of which leaves climate predictors puzzled and water planners nervous.
"From a professional standpoint, I can say the reservoirs are full," said Ester. "From a personal viewpoint, I wish it would keep raining."
RESERVOIR: PERCENT FULL CAPACITY
- Roosevelt -- 98 percent, 1,628,220
- Horse Mesa -- 97 percent, 237,579
- Mormon Flat -- 95 percent, 55,029
- Stewart Mt -- 95 percent, 66,452
- Horseshoe -- 99 percent, 107,871
- Bartlett --100 percent, 178,186
April 9 Flows (cubic feet per second)
- Salt River at Roosevelt 2,200
- Tonto Creek at Roosevelt 92
- Salt River Canyon 1,504
- Verde River (Camp Verde) 199