Tuesday, July 12, 2005


Map of Lake Champlain's bottom unveiled


Rutland Herald
By John Zicconi
July 08, 2005

MIDDLEBURY — Scientists at Middlebury College unveiled a three-dimensional map of Lake Champlain's bottom Thursday, culminating nearly a decade of work that not only discovered more than 70 previously unknown shipwrecks, but is expected to greatly advance pollution-control measures.

The $1 million effort is the first comprehensive attempt to chart the lake's bottom since the U.S. government mapped its depth in 1879, said Art Cohn, executive director of the Lake Champlain Maritime Museum in Vergennes.

The previous survey charted less than 10 percent of the lake bottom, while the new effort captured more than 95 percent, he said."This map is the new baseline that will be used to try and figure out how the lake works," Cohn said.

"It's a quantum-leap advancement in what we understand about the bottom of Lake Champlain."Using state-of-the-art marine survey technology, the husband-and-wife research team of Pat and Tom Manley made nearly 735,000 individual measurements with the help of their students to produce the color-coded map.

Data was collected between 1996 and 2003 from a torpedo-shaped sonar that was towed behind a research vessel.

Thousands of lake sweeps discovered many once unknown shipwrecks, including Benedict Arnold's long-lost battleship, the Spitfire.

Arnold's small navy lost 11 of its 15 ships during the 1776 Battle of Valcour Island near Ticonderoga. The whereabouts of the other ships have long been known — the Philadelphia was raised in 1935 and is displayed in the Smithsonian — but no one knew where the Spitfire was resting until the mapping expedition discovered it during the late 1990s.

Cohn said historians are thrilled about not only finding the Spitfire — "which sits upright on the lake bottom with its cannons ready and searching for an enemy" — but all of the previously unknown wrecks that litter the lake's 400 foot depth.

"The stories and information that come out of these shipwrecks are valuable tools that allow us to understand history," Cohn said. "For the first time, we have an inventory … and now we can begin to prioritize their study and reasonably manage their public access."

Ancient shipwrecks may capture the imagination of many, but scientists believe the new map will help them understand how water in the lake circulates, Tom Manley said. Circulation studies could result in discovering new ways that pollutants like phosphorus and mercury can be reduced, he said.

"We can use circulation models to focus on sediment transportation, mercury transportation and phosphorus transportation," Manley said. "We can use it to get better information on where mercury and sediment settle and hopefully moderate their impacts."

A better understanding of water flows could also lead to a reduction in algae blooms, he said.

The new research uncovered previously unknown shoals, rises, plateaus, old river channels and faults along the lake's floor, Pat Manley said. Now that the bottom's typography is better known, researchers are turning their attention to creating "mosaics" of the lakes different sections so water circulation can be better understood, she said.

The first lake section to be detailed is the so-called "Island Sea" between Malletts and Missisquoi bays, she said.

"This map is only the first of what will be processed from the data collected," Pat Manley said. "We will make mosaics of the entire lake bottom."

The map project was initiated in 1996 as a response to the lake's zebra mussel invasion.While the Manleys believe nothing they have done can stem the invasion, Cohn said their research did uncover the shipwrecks before the mussels had a chance to overtake them.

The Manleys' research was funded through a combination of public and private sources including grants from the Freeman and Lintilhac Foundations.Sen. Patrick Leahy, D-Vt., helped procure about $200,000 from Congress, while another $300,000 was received from other government sources such as the Department of Defense Legacy Program, the National Park Service, and the state Department of Environmental Conservation.

"This lake survey will further the work of scientists and archeologists," said Leahy, who attended the map's unveiling.

"The entire scientific community for years to come will have access to this wonderful tool."

So will the public. Copies of the 8-foot bathymetric map will soon be on display at both the Lake Champlain Maritime Museum and the Echo Lake Aquarium and Science Center in Burlington.


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