Road Salt Blamed for
Rising Salinity in Northeast Streams
September 06, 2005 — By Randolph E. Schmid, Associated Press
WASHINGTON — The amount of salt
dissolved in streams in the Northeast is rising and chemicals used to
clear snow and ice from the roads are being blamed.
"We're basically hardening the watersheds and feeding them a high-salt
diet. There is a direct connection between the number of driveways and
parking lots we have and the quality of our water," said Sujay Kaushal
of the University of Maryland Center for Environmental Science in
Frostburg, Md.
Kaushal and colleagues tested water in streams in rural areas of New
Hampshire, upstate New York and Maryland, comparing the amount of
dissolved salt over several decades. Their findings are reported in
Tuesday's issue of Proceedings of the National Academy of Sciences.
"We think that the salt has built up in the ground water, so even if we
quit applying it, it would still be slightly salty for decades," Kaushal
said in a telephone interview.
There are alternatives methods of deicing, he added, but they have side
effects too. "The problem is the number of roadways," he said, saying
the number being built should be limited.
In New Hampshire's White Mountains, some streams exceeded 100 milligrams
per liter of chloride on a seasonal basis, the researchers said, similar
to the salt level in the mixing region where the Hudson River meets the
ocean.
Salt concentrations measured in the same streams in the 1970s were
around 10 mg per liter, Kaushal said.
A liter is a bit more than a quart and a milligram is about
one-thousandth of the weight of a paper clip. EPA's safe drinking water
limit for salinity is 500 mg per liter.
In streams feeding into Baltimore's reservoirs, salinity increased from
about 10 mg per liter to about 50 mg per liter in the since the 1970s,
while in Dutchess County, N.Y., the increase was from 30 mg per liter to
60 mg per liter since the 1980s, the researchers said.
The study focused on Little Mogan Run, Middle Run and Beaver Run feeding
into Baltimore's Liberty Reservoir; Wappinger Creek and the Mohawk River
in New York State and streams in the Hubbard Brook Valley of New
Hampshire's White Mountains.
The researchers noted that this problem is also occurring in other parts
of the country, with rising salinity reported in some Midwestern lakes.
Overall there are 2.6 million miles of paved roads in the United States,
with new roads being constructed daily. When parking lots and driveways
are factored in, there is already enough blacktopped surface in the U.S.
to cover the entire state of Ohio, they said.
Kevin Farley, a professor of ecology at Manhattan College, said he was
not surprised by the findings as there has been concern about salt
runoff for years. Farley was not part of Kaushal's research team.
The study was funded by the National Science Foundation, the
Environmental Protection Agency and the A. W. Mellon Foundation.
Source: Associated Press |