SOUTH BURLINGTON, Vt. (AP) — The snow hasn't flown yet, but highway crews around Vermont are gearing up for the inevitable — and again find themselves under mounting pressure to reduce the use of ever-costly and corrosive road salt.

Rust and budget concerns aside, the common de-icer, sodium chloride (the same chemical that seasons our food), faces increased scrutiny as a pollutant in streams and lakes.

Chloride, not sodium, is the primary culprit.

Neighboring New Hampshire has begun regulating chloride levels in waterways where road-salt is implicated in health declines in aquatic plants and animals. And Vermont is heading in that direction, experts agree.

"We're viewing it as inevitable," said Justin Rabidoux, South Burlington's director of Public Works, "and we like to get out in front of environmental legislation."

The city was Vermont's first to systematically limit pollution from rain runoff through a separate stormwater utility.

Now, Rabidoux added, his department is mulling ways to persuade public and private snowplow teams to protect waterways — and ultimately, Lake Champlain — from an ever-saltier diet.

The challenges are daunting.

On average, a single winter's road-salt use by Burlington, Colchester, Essex, Shelburne, South Burlington, Williston and Winooski totals about 12,500 tons — an payload that would fill about 1,780 large plow/salt trucks.

That doesn't include the de-icing of Interstate 89 and Vermont state roads in the area.

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A DELICATE BALANCE

As with other fast-growing parts of Chittenden County, South Burlington has steadily built more roads, which adds to the roster of lanes to be salted and plowed.

There is no tidy way to compare various towns' winter salt use: Hilly roads, wider lanes, urban sidewalks and traffic volumes boost the totals.

But, what the municipalities have in common is a priority of motorists' and pedestrians' safety over chloride's environmental costs.

In Shelburne, public opinion for years weighed heavily in favor of increasing the amount of salt on roads, remembers former Selectboard Chairman Al Gobeille, who now leads the Vermont Agency of Human Services.

Current Shelburne Selectboard member Josh Dein recently proposed the town enact a ban on road salt, rather than persisting in its two-year legal challenge to a covered salt-storage facility owned by Vermont Railway.

Dein's gesture strikes many in town as unrealistic.

His risk-assessment, though, is supported in testimony to the House Committee on Natural Resources, Fish and Wildife in January.

Salt on the roads is typically the dominant cause of high chloride levels in waterways — not wastewater plants, agriculture or salt storage, Corrina Parnapy, who manages the federally designated Winooski Natural Resources Conservation District, told the committee.

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GEARING UP FOR LOWER SALT

Parnapy urged lawmakers to support a battery of preventative measures, including: better chloride monitoring; imposing low-salt zones near streams; and the use of brine or other liquid additives that can reduce total salt use, and are effective at lower temperatures.

Better gear in recent years also help reduce salt's collateral damage, while keeping motorists safe, Rabidoux and his colleagues agree.

Plow trucks in many of the surrounding municipalities have steadily become "smarter" as well as brawnier.

At the South Burlington DPW salt shed, Adam Cate, the department's operations manager, demonstrated a truck's high-tech add-ons.

Nestled among the old-school hydraulic controls, electronic sensors monitor road and air temperature.

A GPS device tracks truck speed.

As the many variables of a winter road unfold, an operator can dole out just the optimal measures of salt and other de-icers — and the dosage is recorded every 30 seconds in a digital log.

At the end of each truck's route, the data is downloaded to Cate's computer via a wireless modem perched in his office window.

Every pound of dispensed salt appears on a spreadsheet, storm after storm.

It's a teaching tool as well as an accounts ledger, Cate said: Every operator — including himself — has found ways to reduce "bounce and scatter" of wasted salt into drainage ditches.

"It's not a perfect science," Cate said. "It's something of an art."

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THE CLIMATE FACTOR

Warming trends haven't been doing Vermont winter road crews any favors.

More frequent thaws translate to more salt that washes off a highway, explained Dennis Lutz, public works director for Essex.

"We have more problems on the milder winters when we're floating back and forth around 32 degrees," Lutz said. "If we have an old-fashioned winter where it starts snowing in November and stays on the ground all the way through — we don't put down a lot of salt."

Nonetheless, greater scrutiny of how and when his plow trucks lay down salt has driven down Essex's pound-per-mile by half, he said.

"I think we all have a ways to go," Lutz added. "We're trying to do the right thing."

In neighboring Colchester, Director of Public Works Bryan Osborne said the region's perennial addition of new communities will continue to boost road-salt use for the foreseeable future.

State rules that would limit the amount of chloride allowed in streams (more commonly known as a total maximum daily load, or TMDL) are clearly on the horizon, Osborne said.

"It has the potential of fundamentally changing how snow and ice programs manage the roadways," he continued. "I believe everyone will need to examine alternative methods of de-icing roads."

Osborne remains optimistic.

"As a society, we're pretty good at figuring things out."

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Information from: The Burlington Free Press, http://www.burlingtonfreepress.com