Scientist explains how Lake Champlain became so polluted
ST. ALBANS — There are six key factors over the course of history that brought Lake Champlain to the point of impairment and at which the state needed legislation to address water quality issues, according to Mike Winslow, a staff scientist for Lake Champlain Committee for over 15 years.
Winslow, who was at one time an environmental education teacher at Keewaydin Environmental Education Center, last month spoke about the history of the Lake Champlain watershed and how water quality reached its current levels at the Osher Lifelong Learning Institute in St. Albans.
For the first factor, Winslow went back in history to when glaciers receded, leaving behind Lake Champlain, much larger than its current size. Most of the watershed was underwater, he said.
“If you had a 40 story building on the shores of present day Lake Champlain, it would have been underwater at this time,” Winslow painted the picture.
“Lake Champlain is disappearing,” he said. “It’s filling in … From a geological perspective, lakes are blips on the landscape. They don’t exist for very long.
“That’s the natural progression of all lakes,” Winslow explained. “What our management practices do is determine how fast that happens.”
The second factor has to do with deforestation in the 1800s, he said. The amount of forest cover in New England dropped dramatically as populations increased, hitting a low point in 1860, according to Winslow.
He said research shows that when the forests were removed, all the soil the trees were holding in place washed downstream and ended up in the lake. On the up side, since 1860, forest cover has increased.
“There’s no better land use from a water quality perspective than forest,” he said. “We are reversing that situation, but it’s not undoing what was done in the past.”
The third factor is agriculture and in Vermont, that has always meant livestock, Winslow said.
At the start of the 19th century, there were more sheep in the state than people, he said. According to Winslow, Vermont made the switch from sheep to cows for two reasons: regulation and technology.
The U.S. dropped tariffs on wool from Europe, lowering the price, Winslow said. The U.S. also opened markets in the west where sheep could be raised more economically.
Raising sheep in Vermont became less competitive so farmers switched over to dairy, he said. Farmers stuck with livestock because Vermont’s climate and soils are good for growing grass, but its topography is bad for harvesting it.
“Since the 1960s, we’ve seen a dramatic reduction in the number of dairy farms,” Winslow said. “We have not seen an equally dramatic reduction in the number of milk cows.”
He attributed this to the introduction of industry health requirements, like the pasteurization of milk. Small farms couldn’t produce enough milk to justify their costs of sending it to market, he said.
According to Winslow, some farms increased in size to afford the necessary investments while others went out of business. The ones that remained in production were on the best soil, typically the watershed, where the lake sediment remained post glacier.
Winslow said that’s why there are more farms in Franklin and Addison County than anywhere else in the state.
To fertilize the crops for livestock feed, farmers imported phosphorus into the state for many years from places like Florida and Morocco, he said. Between 1924 through 2007, around 48,000 tons of phosphorus was imported into the state, according to Winslow.
“For a long time, in the ’50s and ’60s, there was no recognition that adding extra phosphorus was anything but good,” he said. “It helped crops grow.”
Ten years later, scientists made the connection between phosphorus and the algae blooms. Since then, the amount of phosphorus added to fields has decreased and the amount coming off the fields has increased, he said.
However, Winslow said, “it’s going to take a long time to undo this 80 to 90 years of bringing in more phosphorus than we were exporting.”
Winslow said he doesn’t know if planting corn for feed is better from a production standpoint, but from a water quality perspective, “corn is terrible for the lake.”
He said, “Grass is definitely better.”
The fourth factor contributing to the cyanobacteria problem in Lake Champlain is the channelization of streams, according to Winslow.
“We’ve changed the way our streams flow,” he said, citing multiple examples of rivers in the state that take right angle turns around important features instead of following its natural course. “In nature, rivers don’t take those right turns.”
“The channelization of streams has consequences,” he continued. “When we straighten streams, we make them steeper,” causing the streams to pick up heavy sediment.
All the extra sediment is delivered down to the lake, Winslow said.
He said the channelization of streams is “difficult to undo.” The state needs major events, like Tropical Storm Irene, to go and un-straighten those streams, he said.
“But as soon as that happens, people want to put them right back where they were,” Winslow continued. “The streams need access to a wider flood plain.”
The fifth contributing factor is developed land, he said. Growing populations means more pavement and wastewater treatment facilities, he said.
Winslow said water runs off pavement instead of absorbing into the ground like it does with soil. Pavement therefore increases the volume of water going into streams, he explained.
He said there’s evidence that cyanobacteria has been a problem in St. Albans Bay since the 1960s. Data collected from the sediment suggests there was an increase in the type of species associated with algae blooms when the wastewater treatment facility was built.
Thirty years later, the phosphorus loading from the wastewater treatment facility was reduced dramatically; however the amount of phosphorus in the sediment in the bay remains about the same, according to Winslow.
“We knew that phosphorus had built up in the sediments and expected that over time it would be depleted,” Winslow said, “but it hasn’t.”
“How we got here is a reflection of the ghosts of what the watershed used to look like in the past,” he said. Lake Champlain’s current state reflects the uses of the watershed fifty years ago rather than today’s usage, he explained.
“The changes we’re making in the policies today, we can’t expect to have immediate (impacts) in the watershed,” Winslow said.
The sixth and final factor is water quality standards, which in Winslow’s opinion are “unrealistic.”
“There are different standards for the different watersheds,” he said. “Where did (the standards) come from to begin with?”
Winslow said in the 1990s, there was a push to develop numeric standards. The people who monitored the lake were asked to label the lake’s health with one of four categories: great, acceptable, not so great, and terrible.
Scientists then correlated the category with the level of phosphorus at the time, according to Winslow.
He said the correlation showed that when the lake’s phosphorus levels were 25 micrograms per liter, there were algae blooms. A one percent chance of seeing algae blooms worked out to be about 14 micrograms per liter, so that became the base amount, according to Winslow.
Some segments of the lake were already below the base level, so their water quality standard was set lower to make sure they didn’t worsen. Where the phosphorus levels were higher and the goal of 14 micrograms per liter unattainable, an aspiration standard was set, according to Winslow.
“As far as I can tell, the numbers were pulled out of thin air,” he said.
Winslow said he’s unsure how certain areas of the lake are going to meet the water quality standards. However, it is the U.S. Environmental Protection Agency’s job to set the standards and the state’s job to figure out how.
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