Embattled de-icer still in driver’s seat in Eagle County
But the science, so far, shows the stuff – used in Eagle County in both the summer and winter – is safe.
“I think the case that this stuff is outright dangerous is very hard to make,” University of Colorado Professor William Lewis has said.
Lewis for three years studied the toxicity of mag chloride in Summit and Clear Creek counties, while the chemical was used to keep Interstate 70 from freezing.
Approximately 600,00 gallons of the de-icer is used by highway crews on Interstate 70 from Wolcott to Vail Pass and on U.S. Highway 24 to Leadville.
The Colorado Association of Ski Towns, an industry advocacy group, also has studied magnesium chloride.
“It appears that these de-icers pose no worse human health impacts than do street sand/salt mixtures,” that study concluded.
Eagle County uses the chemical during the summer to control dust on gravel roads.
“It seems responsible to apply it as a dust inhibitor,” Eagle County Environmental Health Director Ray Merry has said. “The dust impacts from particulates would be much worse.”
Highway crews use magnesium chloride and a variety of other de-icers and traction mixtures to keep I-70 clear during snowstorms.
“(Magnesium chloride) is one of the tools we use and it’s proven effective,” says Keith Powers, the department of transportation’s engineer in Eagle County. “Other than that, we’re always trying to find better products.”
In fact, highway sand, dumped on roads in heavier amounts before magnesium chloride came to Colorado, has been blamed for doing far more serious environmental damage to streams alongside I-70. Millions of dollars are now being spent to keep any more sand from pouring into Black Gore Creek above Vail and Straight Creek above Dillon. Scientists say the sand is choking off the streams and threatening fish, insects and plants.
Lewis has also studied the impact of magnesium chloride on aquatic organisms.
“We don’t have any field evidence of negative effects of mag chloride on aquatic organisms,” he has said, adding the substance is typically diluted to levels where it does little damage once it leaks into streams.
Lewis, however, has noted chloride “burns” on roadside trees. The phenomenon is well known on the East Coast, where sodium chloride is mixed with highway sand, he has said.
“It doesn’t kill the tree, it just turns exposed branches brown,” he said. “It’s unsightly but it doesn’t extend very far from the road.”
The use of magnesium chloride also has been credited with reducing automobile accidents – by as much as 300 percent on some stretches of I-70, according to the department of transportation.
John McCarty, a landscape architect who worked on the Glenwood Canyon revegetation project, has said he thinks magnesium chloride is killing and damaging trees in Snowmass Canyon. On the other hand, he has said, he understands the department of transportation’s predicament.
“It’s easy to sit back and say `They’re holding the environment in low regard,” McCarty has said. “But it all has to do with safety on the highway.”
The department of transportation is just responding to the public’s demands for ice-free roads, McCarty has said.
“We need people to say, `I agree to go at a responsible speed on snowy days,'” McCarty has said. “It’s easy to point a finger, but not many people point a finger at themselves.”
Matt Zalaznick can be reached at 949-0555, ext. 606, or via e-mail at firstname.lastname@example.org.