Tree-ring data gives researchers a better idea of drought history in the Western United States.

Using data from tree rings, University of Arizona researchers conclude the water supply for the Upper Colorado, Salt and Verde river basin fluctuated in synchrony -- at the same time -- during periods of severe drought. The study goes back almost 800 years in the Salt-Verde basin and covers waterways from the states of Arizona, Colorado, New Mexico, Utah and Wyoming.

"Prior to the findings from this study, the conventional wisdom was that runoff from the Colorado River would be available to make up for deficits on the Salt and Verde rivers during times of extreme drought," said Charlie Ester, Salt River Project's manager of Water Resource Operations.

"The bottom line is that the Upper Colorado Basin and the Salt and Verde basins work together as one entire region."

Copyright 2005 by United Press International