News Release
U.S. Department of the Interior
U.S. Geological Survey
March 24, 2006 Glenn Hodgkins 207-622-8201, ext.121
gahodgki@xxxxxxxx
Robert Dudley 207-622-8201, ext.115
rwdudley@xxxxxxxx
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Note to Editors: The report, “Changes in the timing of winter-spring
streamflows in eastern North America, 1913-2002” is available to news media
from the contacts listed above.
Rivers Indicate Earlier Snowmelt in Eastern North America
Scientists at the U.S. Geological Survey (USGS) have found evidence in
eastern North America that the snow is melting and running off into rivers
earlier than it did in the first half of the 20th century. According to a
USGS study published in the most recent issue of Geophysical Research
Letters, winter-spring 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,” explained Glenn Hodgkins, lead author
and hydrologist at the USGS Maine Water Science Center. “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. These rivers are sensitive to changes in precipitation and
temperature,” added Robert Dudley, study co-author.
The scientists compared the dates by which half of the total volume of
winter-spring runoff has flowed past a river gaging station in each year.
Most rivers north of 44° 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.
Changes in average monthly flows support these results—there are high
percentages of rivers north of 44° north latitude with increases in
January, February, and March streamflows and relatively high percentages of
rivers with decreases in May and June.
In 2005, researchers from Scripps Institution of Oceanography and the USGS
found earlier streamflow across large portions of western North America in
rivers with significant snowmelt runoff.
The documented changes in the timing of winter-spring streamflows in
eastern North America may be important to aquatic ecosystems but the
impacts of these changes are not well understood. One possible impact may
be on the survival rate of Atlantic salmon.
The USGS serves the nation by providing reliable scientific information to
describe and understand the Earth; minimize loss of life and property from
natural disasters; manage water, biological, energy, and mineral resources;
and enhance and protect our quality of life.
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