A report from scientists at the U.S. Geological Survey stated that the drought currently gripping the West could be the biggest in 500 years, with effects in the Colorado River basin considerably worse than during the Dust Bowl years, the Associated Press reported.
The report said the drought has produced the lowest flow in the Colorado River on record, with an adjusted annual average flow of only 5.4 million acre-feet at Lees Ferry, Ariz., during the period 2001-2003. By comparison, during the Dust Bowl years, between 1930 and 1937, the annual flow averaged about 10.2 million acre-feet, the report said.
Scientists use tree-ring reconstructions of Colorado River flows to estimate what conditions were like before record-keeping began in 1895. Using that method, the lowest five-year average of water flow was 8.84 million acre-feet in the years 1590-1594. From 1999 through last year, water flow has been 7.11 million acre-feet.
"These comparisons suggest that the current drought may be comparable to or more severe than the largest-known drought in 500 years," the report said.
Environmental groups said the report reinforces the need to figure out a better way to manage the Colorado River before reservoirs run dry.
Droughts seldom persist for longer than a decade, the report noted. But that could mean the current drought is only half over.
"If you're a betting person, you will bet that we will come out of this drought next year," Robert Webb, lead author of the new fact sheet, said. "It's a very severe event and these things tend to end fast. There are other indications, though, that suggest that this drought could persist for as long as 30 years....We really don't know."
Source: Associated Press