UVM study: Lake Champlain is saltier

Lake Champlain Carry Bay
Lake Champlain at Carry Bay in North Hero. Photo courtesy Lake Champlain Basin Program

Lake Champlain is growing increasingly salty, and researchers say winter snow maintenance is the likely culprit, according to a new study published April 10.

Salt in the lake can promote the spread of blue-green algae, according to scientists.

The current salinity level of Lake Champlain isn’t high enough to harm aquatic life, or high enough for humans to taste, scientists say.

Lake Champlain is one of two of the 20 Vermont lakes in the study that are experiencing increasing salinity, and that trend worries some researchers, said Mindy Morales-Williams, a scientist with the Rubenstein Ecosystem Science Laboratory. Morales-Williams will begin teaching as an assistant professor at the University of Vermont in August.

“I think the concern is the increasing trend, and the potential for it to continue to rise,” she said. “It’s currently not at the level [in Lake Champlain] where it would hurt aquatic life … but the problem with salt is that it’s really hard to remove from water, and it’s really hard to remove from soil.

“Even if you stop salt application … it continues to leach” from soil, Morales-Williams said.

Moreover, she said, “larger lakes like Champlain take longer to recover than small lakes because the residence time is longer, meaning things that enter the lake stick around a lot longer than it would in a smaller lake with a shorter residence time.”

The lake has a long ways to go before it reaches what the Environmental Protection Agency defines as the “aquatic life threshold criterion,” which is at 230 milligrams per liter. This concentration, Morales-Williams said, is the point at which “most freshwater aquatic life cannot survive.

“Your lake is basically dying at that point; you’re severely impacting ecosystem function,” she said.

Sampled sites from Lake Champlain show a mean concentration of 11 milligrams per liter.

Even at lower concentrations, salt can affect the balance that exists between organisms living within freshwater water bodies, Morales-Williams said.

Toxic blue-green algae, which as the result of phosphorus pollution throughout the state blooms annually in Lake Champlain, tolerates salt better than most freshwater plant species, Morales-Williams said.

Also known as cyanobacteria, these plants can handle up to a third of the salinity found in ocean water, she said.

As a result, cyanobacteria in salty freshwater lakes can potentially outcompete other, less salt-tolerant species, Morales-Williams said.

“Increasing salinity … may promote blue-green algae” as a result, she said.

The study, published in the scientific journal Proceedings of the National Academy of Sciences, found that impervious surfaces, such as asphalt and concrete, are closely linked with trends of increasing salinity. The study found long-term salinity increasing in lakes where as little as 1 percent of the area within 500 meters of the shoreline is covered with an impervious surface.

Road salt is the most likely culprit, the study found.

But as much as 50 percent of the salt found in some lakes in the study is thought to have come from individuals and businesses applied their own salt, Morales-Williams said.

Lily Pond, in Dover, is also undergoing long-term salinization, Morales-Williams said. The concentration of salt there was measured at less than one milligram per liter, but it showed a long-term increasing trend, she said.

The other 18 Vermont lakes that were included in the study did not show trends of increasing salinity, according to the study’s results.

“Overall, concentrations across the state were quite low, except in Lake Champlain,” Morales-Williams said.

The study includes 371 North American lakes in total, spread out through the United States and Canada.

As a whole, the study indicates a need to carefully weigh the utility of road salt against its consequences in nearby freshwater water bodies, Morales-Williams said.

“We really need to have society work on balancing our needs with how we affect local ecosystems,” she said. “We want ice-free roads right away, but we’re really doing damage to the quality of our water resources.”

The Vermont Agency of Transportation applied 66,821 tons of salt to state roads over the winter spanning 2015 and 2016, according to the VTrans 2017 Fact Book.

During the same period VTrans applied 2,496 cubic yards of sand to road surfaces.

The previous winter VTrans applied 131,684 tons of salt and 6,489 cubic yards of sand.

On average over the past five years, VTrans has applied 114,607 tons of salt each winter, and 5,530 cubic yards of sand.

Road salt, according to the VTrans 2017 Fact Book, “is the primary material used on the majority of roads maintained by VTrans. Salt is used to prevent the bonding of snow and ice onto the pavement surface, and to melt snow and ice that cannot be removed by plowing.”

Salt is generally used when pavement temperatures measure 15 degrees Fahrenheit or above; at lower temperatures, VTrans uses sand “when necessary for temporary traction.”

More detailed results for salinity in each lake researched in the study can be found here.

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  • Kathy Leonard

    What an eye-opener these VTrans numbers are! The internal combustion engine keeps compounding man’s toll on our planet. That along with opposable thumbs have likely sealed our fate, me thinks.

    Thanks for all of this information, Mike.

  • Edward Letourneau

    We have also been killing trees and rusting out cars for a couple of generations — all so people can have totally clear streets and roads. Its time for public discussion on why we are doing this.

    • Peter Chick

      It would be better to teach flatlanders how to drive in snow. The local town manager said salt was hurting a bridge. I suggested less salt and he looked at me like I had two heads. I believe the overuse of salt is in the name of tourism. Bad reason.

      • Julia Purdy

        In the good old days we used chains. In fact, five inches of snow on a road can provide better traction than a slick frozen surface. People who are used to driving rural roads know to place their wheels in the “rough.” That’s how I made it over Sherburne Pass (Killington) one time when the whole line of traffic was stopped and spinning out on ice created by their own exhaust, after one of those fast-moving snow squalls.

    • John Freitag

      It is indeed a problem. Currently we use about 10 tons per mile of salt over the course of the winter taking care of our paved highways in Strafford. People, especially since over the years as we have become much more a commuter society in Vermont, appreciate the roads being cleared but clearly there is an environmental price. Again thanks VTDigger for reporting on another issue most are not yet talking about and certainly deserves our attention.

  • jan van eck

    The problem with road salt goes farther than wrecking the Lake; salt also penetrates into the bridge decking and wrecks steel and concrete bridges. Salt is an all-purpose wrecker.

    I have designed a machine that will remove a thick layer of road ice and whatever snow is left over afer plowing, does it in one pass, does not contact the road surface, and uses no chemicals. The road is left bone dry and clean. The problem is that the machine moves slowly, at the pace of a brisk walk. So, were you to go that route, it would require patience of motorists after a storm, or many machines stationed along a route (costs more). If you mount the machine inside a big frame such as on a fire truck, it could go at say 25 mph between iced-up locations, but that is also more money (but less machines, it is a trade-off).

    These machines could be built in Vermont and sold to other States, a nice new industry employing hundreds. But since they run on diesel engines, it would get sued by the Conservation Law Foundation and VPIRG, and the miscallaneous rabid ideologues, so it ain’t gonna happen. OK, so now you get a polluted Lake instead.

    And that is what happens when the fringe runs your life. You end up with cyanobacteria, dead fish, and a distorted environment. Besides, the ideologues will save the planet instead with their giant windmill propellers, just watch.

    • Finn Yarbrough

      So… could these miracle machines run on properly emission-controlled diesel engines? Or gas engines? Or big electric motors? Somehow I have the feeling that VPIRG is not your biggest obstacle here.

  • Thomas Sperry

    Lake Champlain is like a big cesspool and Vermont and Burlington is to blame.

  • Julia Purdy

    Yet another thing to worry about. “Also known as cyanobacteria, these plants can handle up to a third of the salinity found in ocean water, she said.” – Not sure what this means. From what I’ve read, cyanobacteria exists in oceans already. In fact, it appears to be one of those cradle-of-life substances. Are we, in our continual narcissism, just treating every naturally-occurring phenomenon that we happen to discover, as an abnormal development, never before seen, just because WE haven’t seen it before? How long have humans beings been on this earth, in geological time? The earth is extremely complex. Can we say we really understand where we stand in the chain of cause and effect that has been going on all that time? Are we trying to literally stop time and change (i.e., evolutionary processes) because we find them inconvenient/threatening? And are we trying to take credit in our inimitably narcissistic way, for being both the cause and the solution?

    • Matthew Davis

      The reference is related to certain strains of cyanobacteria (blue-green algae) that occur in Lake Champlain and increase in number when excess phosphorus is available. Their point is that these algae are more tolerant of higher salt levels and therefore could out compete other forms of algae thus leading to larger populations of the toxic to life forms.