Heavy rains have small impact on reservoirs

 

Roosevelt Lake, about 100 miles northeast of downtown Phoenix, received only about an inch of rain from last week’s storm and recorded no significant increase in its water level. (U.S. Bureau of Reclamation Photo)

By STEPHEN HAMWAY
Cronkite News 

PHOENIX – For all the problems last week’s record-breaking storm caused across the greater Phoenix area, from flooded highways to property damage, those who endured it won’t get much of a payoff at their taps.

Three-plus inches of rain at Phoenix Sky Harbor International Airport – with reports of far more elsewhere in the Valley – didn’t provide any real boost to area reservoirs.

“It really didn’t move the dial much at all,” said Scott Harelson, media relations supervisor at Salt River Project.

There may have been a negligible increase at Roosevelt Lake, largest of SRP’s reservoirs along the Salt River, but the level remained at 38 percent full from Sept. 7 to Sept. 9.

“We’ll take everything we can get, obviously, but it’s really pretty negligible,” Harelson said.

Part of the reason, according to Harelson, is that the worst of the storm centered on the Valley rather than areas east and northeast where SRP’s six reservoirs lie. Roosevelt Lake, just over 100 miles from downtown Phoenix, received less than an inch of rain as the Phoenix area flooded on Sept. 8.

More significant, Harelson noted, is that monsoon season produces very little of SRP’s water.

“It’s not that unusual for summer storms to not affect water levels,” he said. “Our water supply is heavily dependent on the snowpack.”

Harelson estimated that 80 percent of the water in SRP’s reservoirs is runoff from winter storms that deposit snow in the high country.

Despite the unimpressive totals, Harelson added that the total runoff for this monsoon season is about 125 percent of normal.

The story was similar at Lake Pleasant, a reservoir north of Phoenix that’s part of the Central Arizona Project. It reported a 1 percent rise in water level, from 56 percent up to 57 percent full. The reservoir is fed by the Central Arizona Project aqueduct as well as the Agua Fria River.

“It all depends on where the storm is,” said David Chatfield, administrative assistant with Lake Pleasant. “The more rain we get up north, the more water there is in the Agua Fria.”

While Hurricane Odile is expected to drop more rain on Arizona this week, spokesmen at both reservoirs expected a negligible change in water levels.

“It will generate some runoff, but not a whole lot,” Harelson said. “There’s plenty of room in the reservoir.”

David Jordan, park supervisor at Lake Pleasant, said he is more concerned about access roads being flooded.

“It’s definitely a concern,” he said. But the park itself drains pretty well.”

  Phoenix-area reservoirs:  

• Roosevelt Lake, SRP

• Apache Lake, SRP

• Canyon Lake, SRP

• Saguaro Lake, SRP

• Horseshoe Reservoir, SRP

• Bartlett Lake, SRP