Lake
Champlain is among the largest natural lakes in the United
States. Geologically
and ecologically Lake Champlain is a sibling of the Great
Lakes. About 18,000 years ago much of the northeastern and
north central United States was covered by a thick blanket
of ice which extended skyward at least far enough to cover
Mt. Mansfield, Vermont's highest peak (1341 m above sea level).
As the last glacial period came to an end, the glaciers retreated
to the north leaving a large body of freshwater which included
the Great Lakes, Lake Champlain, and much of the St. Lawrence
River valley. As the glaciers continued to recede, sea water
from the Atlantic Ocean flooded into the St. Lawrence valley
and the Champlain valley creating the Champlain Sea (about
11,000 years ago). Over the next few thousand years, the land
of the Champlain Valley, relieved of the burden of a thick
layer of ice, gradually rebounded. As the water flowed northward
into the St. Lawrence River, the sea water was replaced and
diluted by freshwater from the surrounding basin.
For
students and researchers of lake ecology, Lake Champlain is
a terrific resource - truly a great lake. Lake Champlain supports
biological communities similar to those found in the Great
Lakes, but it has not experienced the same intensity of human
settlement, impacts, or commercial utilization as its five
larger "siblings". It therefore provides an excellent basis
for comparison studies of large lake ecology.
Water
quality in the lake and its tributaries is influenced by a
combination of municipal, industrial, agricultural, and recreational
uses throughout a relatively large area of two U.S. states
and one Canadian province. The Lake Champlain Basin includes
a small bit of southern Quebec, a large portion of upstate
New York, and most of the state of Vermont. Water from the
lake flows slowly northward into Canada's Richelieu River
and empties into the St. Lawrence River. Environmental decisions
regarding the lake and it's basin, therefore, must include
interstate and international cooperation.
Lake
Champlain is geologically subdivided into five distinctly
different sub-basins, each of which represents a somewhat
different set of limnological conditions. The South Lake (from
the Poultney River north to Crown Point) is quite narrow,
shallow, and turbid - much like a large, slow river. On the
northern end of Lake Champlain lies Missisquoi Bay, a very
shallow (< 4.5 m deep) and turbid part of the lake that
receives water from both the state of Vermont and the Province
of Quebec. Missisquoi Bay flows south into the Inland Sea,
also known as the Northeast Arm. This rather large section
of Lake Champlain lies to the east the Champlain Islands (South
Hero, North Hero, and Isle LaMotte). Although fringed by some
warm, shallow bays, much of the Inland Sea is fairly deep
(over 30 m), cool, and relatively clear. South of the Inland
Sea lies Malletts Bay - a rather small basin with restricted
exchange with the rest of the lake due to a highway causeway
on its north side (US Route 2) and a former railroad causeway
on its west side. Over 80% of the volume of the entire lake
is contained within the Main Lake, also known as the Broad
Lake. This section runs from Crown Point north to Rouses Point,
where the lake flows into the Richeleau River on its way to
the St. Lawrence River and, eventually, the Atlantic Ocean.
The Main Lake is quite deep, with much of it over 60 m and
a few locations over 120 m in depth. Much of the Main Lake
is clear and cold. The limnological diversity provided by
these five sub-basins makes Lake Champlain all the more interesting
and challenging for those interested in large lake ecology.
Lake
Champlain is geologically subdivided into five distinctly
different sub-basins, each of which represents a somewhat
different set of limnological conditions. The South Lake (from
the Poultney River north to Crown Point) is quite narrow,
shallow, and turbid - much like a large, slow river. On the
northern end of Lake Champlain lies Missisquoi Bay, a very
shallow (< 4.5 m deep) and turbid part of the lake that
receives water from both the state of Vermont and the Province
of Quebec. Missisquoi Bay flows south into the Inland Sea,
also known as the Northeast Arm. This rather large section
of Lake Champlain lies to the east the Champlain Islands (South
Hero, North Hero, and Isle LaMotte). Although fringed by some
warm, shallow bays, much of the Inland Sea is fairly deep
(over 30 m), cool, and relatively clear. South of the Inland
Sea lies Malletts Bay - a rather small basin with restricted
exchange with the rest of the lake due to a highway causeway
on its north side (US Route 2) and a former railroad causeway
on its west side. Over 80% of the volume of the entire lake
is contained within the Main Lake, also known as the Broad
Lake. This section runs from Crown Point north to Rouses Point,
where the lake flows into the Richeleau River on its way to
the St. Lawrence River and, eventually, the Atlantic Ocean.
The Main Lake is quite deep, with much of it over 60 m and
a few locations over 120 m in depth. Much of the Main Lake
is clear and cold. The limnological diversity provided by
these five sub-basins makes Lake Champlain all the more interesting
and challenging for those interested in large lake ecology.