Sunday, March 30, 2008

Wet winter raises water levels for Arizona, but drought persists

Arizona Republic: …..Runoff from the winter's bounty has nearly filled Roosevelt Lake, which was almost half-empty at the end of last summer. It's still possible the reservoir will reach full capacity for the first time since the dam was raised 77 feet in 1996.

That's good news for Valley cities, which draw much of their water supplies from the lake and its sibling reservoirs on the Salt and Verde rivers. But experts say they can't yet call an end to the state's ongoing drought. A wet year often interrupts long dry spells, and in the desert, dry spells can easily span 20 years.

… SRP's reservoirs will near capacity for just the second time in more than a decade. (Although 2005 produced more runoff, the reservoirs began with less water then than this year.) The gush of runoff allowed SRP to cancel an order for Colorado River water and reduce planned groundwater pumping from an estimated 275,000 acre-feet to just 75,000 acre-feet.
The two reservoirs on the Verde River, Horseshoe and Bartlett, filled by the end of January, which forced SRP for several weeks to divert the overflow downstream into the lower Salt, through Tempe Town Lake and on to the Gila River near Avondale.
Most of the snow has melted on the Verde watershed, and the Salt River has reached its expected peak. As of Friday, Roosevelt Lake had risen to 97 percent of capacity, its water levels 12 feet higher than the top of the old dam, 6 inches higher than the peak set in 2005 and just 3 feet below the full mark….

Climate experts won't declare a drought over on the strength of one wet year, especially not in the middle of such a persistent dry period. Full reservoirs paint only a partial picture of water and climate conditions in Arizona. Most rural communities rely on groundwater that still suffers from significant moisture deficits. Water managers also must watch the Colorado River, which supplies the state with about one-third of its water….

2004 photo of Arizona border welcome sign by Wing-Chi Poon, Wikimedia Commons

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