The U.S. Geological Survey says eastern North America is having snow melt and runoff into rivers earlier than it did in the first half of the 20th century.
The study, published in Geophysical Research Letters, says flows in many rivers in the northern United States and Canada are occurring earlier by 5-10 days.
"We studied rural, unregulated rivers with more than 50 years of USGS and Environment Canada river flow data," said lead researcher Glenn Hodgkins at the USGS Maine Water Science Center.
Most rivers north of 44 degrees north latitude -- roughly from southern Minnesota and Michigan through northern New York and southern Maine -- showed earlier winter-spring streamflows. In contrast, many stations south of this line in Iowa, southern Wisconsin and northern Illinois had later streamflows.
"Some 179 rivers in eastern North America met the criteria of our study with 147 in the United States from the Dakotas to New England and 32 in Canada from Manitoba to Newfoundland," said co-author Robert Dudley. "These rivers are sensitive to changes in precipitation and temperature."
Copyright 2006 by United Press International
Explore further: The Large Synoptic Survey Telescope: Unlocking the secrets of dark matter and dark energy