A map showing the Great Lakes.
The Great Lakes
are a collection of freshwater lakes
eastern North America
, on the Canada – United States
. Consisting of Lakes Superior, Michigan, Huron, Erie, and
Ontario, they form
the largest group of freshwater lakes on Earth.
They are sometimes referred to as the
" by some citizens of the
United States. Because of their size, types of ecosystems
, and large abundances of beaches
along their coasts, some regard them as inland
or as one sea.
The Great Lakes region contains not only the five main lakes
themselves, but also numerous minor lakes and rivers, as well as
approximately 35,000 islands.
Ste. Marie, ON
Ste. Marie, MI
average depths, maximum depths, and volumes of the Great
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$avgdepth at:117 shift:(0,1) text:"483 ft (147 m)"
$maxdepth at:-732 text:"1,332 ft (406 m)"
bar:Michigan from:-348 till:577 width:113 color:blue5
$elevation at:577 text:"577 ft (176 m)"
$avgdepth at:298 shift:(0,2) text:"279 ft (85 m)"
$maxdepth at:-348 text:"925 ft (282 m)"
bar:Huron from:-173 till:577 width:101 color:blue3
$elevation at:577 text:"577 ft (176 m)"
$avgdepth at:382 shift:(0,1) text:"195 ft (59 m)"
$maxdepth at:-173 text:"750 ft (229 m)"
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$elevation at:569 text:"569 ft (173 m)"
$avgdepth at:507 align:left shift:(30,2) textcolor:textoutsidebar text:"62 ft (19 m)"
$maxdepth at:359 text:"210 ft (64 m)"
bar:Ontario from:-559 till:243 width:44 color:blue4
$elevation at:243 text:"243 ft (74 m)"
$avgdepth at:-40 shift:(0,2) text:"283 ft (86 m)"
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||The area of each rectangle is proportionate to the volume of
each lake. All measurements at Low Water Datum.
Lakes Michigan and Huron are hydrologically a single lake,
sometimes called Lake
; they have the same surface elevation of
, and are connected not by a river but by the deep Straits of Mackinac.
Other bodies of water
- Georgian Bay is a large bay located within Lake Huron, separated
by the Bruce
Island. It contains the majority of the islands of
the Great Lakes, with a count of approximately 30,000. The North
Channel, a narrower westerly extension of Georgian Bay,
separates Manitoulin Island from mainland Northern Ontario.
Mackinac connects Lake Michigan to Lake Huron.
Canal connects Lake Erie to Lake Ontario, bypassing the
River which cannot be fully navigated due to the presence
- Lake St. Clair is the smallest lake in the Great Lake system but
due to its relatively small size (compared to the five "Great
Lakes"), it is rarely, if ever, considered a Great
- Lake Nipigon to the north of Lake Superior was formed by an
extension or aulacogen of the Midcontinent Rift System which also
formed Lake Superior, so the two lake beds are connected by shared
geology. Lake Nipigon is sometimes called the sixth Great
Dispersed throughout the Great Lakes are approximately 35,000 islands
. The largest among
them is Manitoulin
Island in Lake Huron, the largest island in any inland
body of water in the world. The second-largest island is Isle Royale in Lake Superior. Both of these islands
are large enough to contain multiple lakes themselves — Manitoulin
Manitou is listed in the Guinness Book of World Records as
the world's largest lake located on a freshwater
Connection to ocean and open water
The Saint Lawrence Seaway
Great Lakes Waterway
Great Lakes to ocean-going vessels. The move to wider ocean-going
container ships — which do not fit through the lock
on these routes — has limited shipping on
the lakes. Despite their vast size, large sections of the Great
Lakes freeze over in winter, interrupting most shipping. Some
ply the lakes.
The Great Lakes are also connected to the Gulf of Mexico by way of
the Illinois River (from Chicago) and the Mississippi River. An
alternate track is via the Illinois River (from Chicago), to the
Mississippi, up the Ohio, and then through the Tennessee-Tombigbee Waterway
(combination of a series of rivers and lakes and canals), to Mobile
Bay and the Gulf. Commercial tug-and-barge traffic on these
waterways is heavy.
Pleasure boats can also enter or exit the Great Lakes by way of the
and Hudson River in New York.
The Erie Canal connects to the Great Lakes at the east end of Lake
Erie (at Buffalo, NY) and at the south side of Lake Ontario (at
are bound by the Canadian province of Ontario and the U.S. states of Minnesota, Wisconsin, Michigan, Illinois, Indiana, Ohio, Pennsylvania, and New
However, not all of the lakes border on all
of these regions. Four of the five lakes form part of the
Canada-United States border; the fifth, Lake Michigan, is contained
entirely within the United
States. The Saint Lawrence River, which marks the
same international border for a portion of its course, is the
primary outlet of these interconnected lakes, and flows through
Quebec and past
Peninsula to the northern Atlantic Ocean.
Great Lakes Circle Tour
The Great Lakes Circle Tour
is a designated scenic road system connecting all of the Great
Lakes and the St. Lawrence River.
|Origins of Name
||Erie ; shorten form of Iroquoian word Erielhonan or “long tail”
||Named by French explorers for inhabitants in the area, Wyandot or “Hurons”
||Likely from the Ojibwa word
mishigami meaning “great water”
||Wyandot (Huron) word ontarío meaning
“Lake of Shining Waters”
||English translation of French term “lac supérieur”
The Great Lakes contain roughly 22% of the world’s fresh surface
water: , or 6.0×1015
liters). This is enough water to cover the 48
contiguous U.S. states to a uniform depth of . However, only 2% of
this volume is replaced each year, causing water levels to fall in
recent years as the water undergoes heavy human use . Although the
lakes contain a large percent of the world's fresh water, the Great
Lakes supply only a small portion of America's drinking water
combined surface area of the lakes is
approximately —nearly the same size as the United
Kingdom, and larger than the U.S. states of New York, New
Jersey, Connecticut, Rhode
Island, Massachusetts, Vermont and New
The Great Lakes coast
measures approximately ;
however, the length of a coastline is impossible to measure exactly
and is not a well-defined measure (see Coastline paradox
A diagram of the formation of the
It has been estimated that the foundational geology which created
the conditions shaping the present day upper Great Lakes was laid
from 1.1 to 1.2 billion years ago, when two previously fused
split apart and
created the Midcontinent
. A valley was formed providing a basin that eventually
became modern day Lake Superior. When a second fault line, the
Saint Lawrence rift
formed approximately 570 million years ago, the basis for
Lakes Ontario and Erie were created, along with what would become
the St. Lawrence River.
The Great Lakes are estimated to have been formed at the end of the
last ice age
(i.e. about 10,000
years ago), when the Laurentide ice
receded. The retreat of the ice sheet left behind a
large amount of meltwater (see Lake Agassiz) which filled up the basins that the glaciers had
carved, thus creating the Great Lakes as we know them today.
Because of the uneven nature of glacier erosion
, some higher hills became Great Lakes islands
. The Niagara Escarpment
follows the contour of
the Great Lakes between New York and Wisconsin.Land below the
as it was
uncovered. Because the glaciers covered some areas longer than
others, this glacial rebound occurred at different rates. Some
researchers believe that differential has contributed to
fluctuating water levels throughout the Great Lakes basin.
The effect of Great Lakes on weather in the region is called the
the moisture picked up by the prevailing winds from the west can
produce very heavy snowfall, especially along lake shores to the
east such as Michigan, Ohio, Pennsylvania, Ontario, and New York.
The lakes also moderate seasonal temperatures somewhat, by
absorbing heat and cooling the air in summer, then slowly radiating
that heat in autumn. This temperature buffering produces areas
known as "fruit belts", where fruit typically grown farther south
can be produced. Western
Michigan has apple and cherry orchards, and vineyards adjacent
to the lake shore as far north as the Grand Traverse Bay. The eastern shore of Lake Michigan and the
southern shore of Lake Erie have many wineries as a result of this,
as does the Niagara
Peninsula between Lake Erie and Lake Ontario.
phenomenon occurs in the Finger Lakes region of New York as well as Prince
Edward County, Ontario on Lake Ontario's northeast shore.
to lake effect, is the occurrence of fog
medium-sized areas, particularly along the shorelines of the lakes.
This is most noticeable along Lake Superior's shores, due to its
The Great Lakes have been observed to help strengthen storms, such
as Hurricane Hazel
in 1954, and a
frontal system in 2007
spawned a few tornadoes in Michigan and Ontario, picking up warmth
from the lakes to fuel them. Also observed in 1996, was a rare
Lake Huron, dubbed the 1996 Lake
The lakes are extensively used for transport
, though cargo
traffic has decreased considerably in recent years. The Great Lakes Waterway
makes each of the
brigantine Le Griffon, which was
commissioned by René Robert
Cavelier, Sieur de La Salle, was built at Cayuga Creek, near
the southern end of the Niagara River, and became the first sailing ship to travel the
upper Great Lakes on August 7, 1679.
A woodcut of Le Griffon
During settlement, the Great Lakes and its rivers were the only
practical means of moving people and freight. Barges
from middle North America were able to reach
the Atlantic Ocean from the Great Lakes when the Erie Canal
opened in 1825. By 1848, with the
opening of the Illinois and Michigan Canal at Chicago, direct access to the Mississippi River was
possible from the lakes.
With these two canals an all-inland
water route was provided between New York City and New
The main business of many of the passenger lines in the 1800s was
. Many of the
larger cities owe their existence to their position on the lakes as
a freight destination as well as for being a magnet for immigrants.
After railroads and surface roads developed, the freight and
passenger businesses dwindled and, except for ferries and a few
foreign cruise ships, has now vanished.
The immigration routes still have an effect today. Immigrants often
formed their own communities and some areas have a pronounced
ethnicity, such as Dutch, German, Polish, Finnish, and many others.
Since many immigrants settled for a time in New England before
moving westward, many areas on the U.S. side of the Great Lakes
also have a New England feel, especially in home styles and
Since general freight these days is transported by railroads and
trucks, domestic ships mostly move bulk cargoes, such as iron ore
for the steel
industry. The domestic bulk freight developed because of the nearby
mines. It was more economical to transport the ingredients for
steel to centralized plants rather than try to make steel on the
spot. Ingredients for steel, however, are not the only bulk
shipments made. Grain exports are also a major cargo on the
In the 19th and early 20th centuries, iron and other ores such as
copper were shipped south on (downbound ships), and supplies, food,
and coal were shipped north (upbound). Because of the
location of the coal fields in Pennsylvania and West Virginia, and the general northeast track of the Appalachian
Mountains, railroads naturally developed shipping routes that
went due north to ports such as Erie, Pennsylvania and Ashtabula, Ohio.
Because the lake maritime community largely developed
independently, it has some distinctive vocabulary. Ships, no matter
the size, are called boats
. When the sailing ships gave
way to steamships, they were called steamboats
term used on the Mississippi. The ships also have a distinctive
design (see Lake freighter
that primarily trade on the lakes are known as lakers
. Foreign boats are known as
One of the more common sights on the lakes is the
1,000‑by‑105 foot (305-by-32 m), self-unloader. This is a
laker with a conveyor belt system that can unload itself by
swinging a crane over the side.
Today, the Great Lakes fleet is much smaller in
numbers than it once was because of the increased use of overland
freight, and a few larger ships replacing many small ones.
The Great Lakes are today used as a major mode of transport
for bulk goods. In 2002,
162 million net tons
of dry bulk cargo were
moved on the Lakes. This was, in order of volume: iron ore, grain,
. The iron ore and much of the
stone and coal are used in the steel industry. There is also some
shipping of liquid and containerized cargo but most container ships
cannot pass the locks on the Saint Lawrence Seaway because the
ships are too wide. The total amount of shipping on the lakes has
been on a downward trend for several years.
The Great Lakes are used to supply drinking water to tens of
millions of people in bordering areas. This valuable resource is
collectively administered by the state and provincial governments
adjacent to the lakes.
Recreational boating and tourism are major industries on the Great
Lakes. A few small cruise ships operate on the Great Lakes
including a couple of sailing ships
fishing, commercial fishing, and Native American fishing represent
a US$4 billion a year industry with salmon
, and walleye
being major catches. In addition, all kinds
of water sports can be found on the lakes. Unusually for inland
waters, the Great Lakes proved the possibility of surfing
, particularly in winter due to the
effect of strong storms and waves.
Great Lakes Passenger Steamers
From 1844 through 1857, palace
carried passengers and cargo around the Great Lakes.
Throughout the 20th century, large luxurious passenger steamers
sailed from Chicago all the way to Detroit and Cleveland. These
were primarily operated by the Detroit & Cleveland Navigation
Company. Several ferries currently operate on the
Great Lakes to carry passengers to various islands, including Isle
Island, Beaver Island, both Bois Blanc
Island, South Bass Island, North Manitou Island, South Manitou Island, Harsens
Island, Manitoulin Island, and the Toronto Islands. As of 2007, three car ferry services cross
the Great Lakes, two on Lake Michigan: a steamer from Ludington,
Michigan to Manitowoc, Wisconsin and a high speed catamaran from Milwaukee to Muskegon, Michigan, and one on Lake Erie: a boat from Kingsville, Ontario, or Leamington, Ontario to Pelee
Island, Ontario then onto Sandusky, Ohio. An
international ferry across Lake Ontario from Rochester,
New York to Toronto ran during 2004 and 2005, but is no longer in
Some Passenger Steamers
The large size of the Great Lakes increases the risk of water
are common threats. The lakes are prone to sudden and severe
storms, particularly in the autumn, from late October until early
December. Hundreds of ships have met their end on the lakes. The
greatest concentration of shipwrecks lies near Thunder Bay
, beneath Lake Huron,
near the point where eastbound and westbound shipping lanes
coast from Grand
Marais, Michigan to Whitefish Point
became known as the "Graveyard of the Great Lakes".
vessels have been lost in the Whitefish Point area than any other
part of Lake Superior. The Whitefish Point Underwater
serves as an underwater museum to protect the many
shipwrecks in this area.
The first shipwreck was the Griffin, the first ship to sail the
Great Lakes. Caught in a storm while trading furs between Green Bay
and Michilimacinac, it sank during a storm and has possibly been
found. The last major freighter wrecked on the
lakes was the SS Edmund Fitzgerald, which sank on November 10, 1975, just over
offshore from Whitefish Point. The largest loss of
life in a shipwreck out on the lakes may have been that of the
Elgin, wrecked in 1860 with the loss of around 400
In an incident at a Chicago dock in 1915, the
rolled over while
loading passengers, killing 841.
In August 2007, the Great Lakes Shipwreck Historical Society
that it had found the wreckage of Cyprus
, a long,
carrier. Cyprus sank
during a Lake Superior storm on October 11, 1907, during its second
voyage while hauling iron ore from Superior, Wisconsin, to Buffalo, New York.
The entire crew of 23 drowned, except one,
a man named Charles Pitz, who floated on a life raft for almost
In June 2008 deep sea divers
Ontario found the wreck of the 1780 Royal
in what has been described as an
"archaeological miracle". There are no plans to raise her as the
site is being treated as a war grave.
Political issues and legislation
Great Lakes water use and diversions
The International Joint
was established in 1909 to help prevent and resolve
disputes relating to the use and quality of boundary waters, and to
advise Canada and the United States on questions related to water
resources. Concerns over diversion of Lake water are of concern to
both Americans and Canadians. Some water is diverted through the Chicago River to operate the Illinois Waterway but the flow is limited
Possible schemes for bottled water plants and
diversion to dry regions of the continent raise concerns. Under the
U.S. "Water Resources Development Act"
, diversion of water from the Great Lakes Basin
requires the approval of
all eight Great Lakes governors through the Great Lakes Commission
, which rarely
occurs. International treaties regulate large diversions. In 1998,
the Canadian company Nova
won approval from the Province of Ontario to withdraw of
Lake Superior water annually to ship by tanker to Asian countries.
Public outcry forced the company to abandon the plan before it
began. Since that time, the eight Great Lakes Governors and the
Premiers of Ontario and Quebec have negotiated the Great Lakes-St.
Lawrence River Basin Sustainable Water Resources Agreement 
and the Great Lakes-St. Lawrence River
Basin Water Resources Compact 
that would prevent most future diversion
proposals and all long-distance ones. The agreements also
strengthen protection against abusive water withdrawal practices
within the Great Lakes basin. On December 13, 2005, the Governors
and Premiers signed these two agreements, the first of which is
between all ten jurisdictions. It is somewhat more detailed and
protective, though its legal strength has not yet been tested in
court. The second, the Great Lakes
, has been approved by the state legislatures of all
eight states that border the Great Lakes as well as the U.S.
Congress, and was signed into law by President George W. Bush
on 3 October 2008.
Coast Guard live fire exercises
In 2006, the United States
(USCG) proposed a plan to designate 34 areas in the
Great Lakes, at least five miles (8 km) offshore, as permanent
safety zones for live fire machine gun practice. In August 2006 the
plan was published in the Federal
. The USCG reserved the right to hold target practice
whenever the weather allowed with a two hour notice. These firing
ranges would be open to the public when not in use. In response to
requests from the public, the Coast Guard held a series of public
meetings in nine U.S. cities to solicit comment. During these
meetings many people voiced concerns about the plan and its impact
on the environment.
A preliminary health risk assessment stated that the "proposed
training will result in no elevated risks for a freshwater system
such as the Great Lakes using 'realistic worst case' assumptions,
and further investigation is not recommended ... if typical rather
than worst case assumptions were used, the predicted risk would be
even less." However, the assessment was based on lead levels after
five years, and so one could infer that lead levels could meet or
exceed EPA safe levels for lead after fifteen years. The Coast
Guard established an information page about their proposal at
On December 18, 2006, the Coast Guard announced its decision to
withdraw the entire proposal. Officials said they would look into
alternative ammunition, modifying the proposed zones and have more
public dialogue before proposing a new plan.
Great Lakes Collaboration Implementation Act
During the 109th United
in 2006, the Great Lakes Collaboration Implementation Act
(Bill HR5100) was introduced to enact the recommendations of the
Great Lakes Regional
, an effort established in 2004 to produce a
strategy for restoring and maintaining the Great Lakes. The bill
was introduced by U.S. senators
and Carl Levin
, along with representatives
and Rahm Emanuel
The bill states that "the Great Lakes are on the brink of an
ecologic catastrophe" and that "if the pattern of deterioration is
not reversed immediately, the damage could be irreparable". It
cites the closing of over 1,800 beaches in 2003, the dead zone
in Lake Erie, and the US$500
million damage each year due to the zebra
as evidences that "a comprehensive restoration of the
system is needed to prevent the Great Lakes from collapsing".
A press release states that the bill aims to stop the introduction
and spreading of invasive species
prevent the Asian carp
from invading the
Great Lakes, phase out mercury
restore animal habitats
, and prevent
A coalition called Healing Our Waters
,or HOW was formed by several
environmental groups and foundations in 2005 to educate and assist
citizens in advocating for the cleanup of the Great Lakes.
Additions to the five Great Lakes
Champlain, a lake
on the border between upstate New York and northwestern Vermont
that is part of the Saint Lawrence-Great Lakes Watershed, briefly
became labeled by the U.S. government as the sixth "Great Lake of
States" on March 6, 1998, when President Clinton signed Senate Bill
927. This bill, which reauthorized the National Sea Grant Program,
contained a line penned by Senator Patrick
Leahy (D-VT) declaring Lake Champlain to be a Great Lake.
Not coincidentally, this
status allows neighboring states to apply for additional federal
research and education funds allocated to these national resources.
was viewed with some amusement by other countries, particularly in
the Canadian media, and the lake is
small compared to other Canadian lakes (such as Great Bear
Lake which has over 27 times more surface area).
Following a small uproar (and several New York Times
and Time Magazine
articles), the Great Lake
status was rescinded on March 24, 1998 (although Vermont
universities continue to receive funds to monitor and study the
Similarly, there has been interest in making Lake St. Clair a Great
Lake. In October 2002, backers planned to present such a proposal
at the Great Lakes Commission
annual meeting, but ultimately withheld it as it appeared to them
to have too little support.
The ecological history of the Great Lakes includes both great
losses and enormous recovery; the system today is in the
most-obvious ways much healthier than it was a half-century ago,
while in less-apparent ways it remains seriously compromised.
Before the arrival of Europeans, the Great Lakes provided fish
to the indigenous
lived near them. Early European settlers were astounded by both the
variety and quantity of fishes; there were 150 different species in
the Great Lakes. Historically, fish populations were the early
indicator of the condition of the Lakes, and have remained one of
the key indicators even in the current era of sophisticated
analyses and measuring instruments. According to the bi-national
(U.S. and Canadian) resource book, The Great Lakes: An
Environmental Atlas and Resource Book
, "the largest Great
Lakes fish harvests were recorded in 1889 and 1899 at some 67,000
tonnes [147 million pounds]," though the beginning of environmental
impacts on the fish can be traced back nearly a century prior to
By 1801, the New York
found it necessary to pass regulations curtailing
obstructions to the natural migrations of Atlantic salmon from Lake
Erie into their spawning channels. In the early nineteenth century,
government found it
necessary to introduce similar legislation prohibiting the use of
weirs and nets at the mouths of Lake Ontario’s tributaries. Other
protective legislation was passed as well, but enforcement remained
difficult and often quite spotty.
On both sides of the Canada–United States border, the proliferation
and impoundments multiplied,
necessitating more regulatory efforts. The decline in fish
populations was unmistakable by the middle of the nineteenth
century, as the obstructions in the rivers prevented salmon
reaching their spawning grounds. The decline in salmon was
recognized by Canadian officials and reported as virtually a
complete absence by the end of the 1860s. The Wisconsin Fisheries
Commission noted a reduction of roughly 25 percent in general fish
harvests by 1875. Many Michigan rivers sport multiple dams that
range from mere relics to those with serious loss of life
potential. The state's dam removal budget has been frozen in recent
years; in the 1990s, the state was removing 1 dam per year.
Overfishing was cited as responsible for the decline of the
population of various whitefish
, important because of their
culinary desirability and, hence, economic consequence. Moreover,
between 1879 and 1899, reported whitefish harvests declined from
some 24.3 million pounds (11 million kg) to just over 9
million pounds (4 million kg). Recorded sturgeon catches fell
from 7.8 million pounds (1.5 million kg) in 1879 to 1.7
million pounds (770,000 kg) in 1899. The population of giant
freshwater mussels was eliminated as the mussels were harvested for
use as buttons by early Great Lakes entrepreneurs
There were, however, other factors in the population declines
besides overfishing and the problems posed by water obstructions.
in the Great Lakes region removed
tree cover near stream channels which provide spawning grounds, and
this affected necessary shade and temperature-moderating
conditions. Removal of tree cover also destabilized soil, allowing
soil to be carried in greater quantity into the streambeds, and
even brought about more frequent flooding. Running cut logs down
the Lakes’ tributary rivers also stirred bottom sediments. In 1884,
the New York Fish Commission determined that the dumping of sawmill
waste (chips and sawdust) was impacting fish populations.
development of ecological problems in the Great Lakes, it was the
influx of parasitic lamprey populations
after the development of the Erie Canal and the much later Welland Canal that led to the two federal governments attempting
to work together.
Despite a variety of efforts to eliminate
or minimize the lamprey, by the mid 1950s the lake trout
populations of Lakes Michigan and Huron were reduced by about 99%,
with the lamprey deemed largely to blame. This led to the launch of
the bi-national Great Lakes Fishery Commission.
Other ecological problems in the Lakes and their surroundings have
stemmed from urban runoff and sprawl, sewage disposal, and toxic
industrial effluent. These, of course, also affect aquatic food
chains and fish populations. Some of these glaring problem areas
are what attracted the high-level publicity of Great Lakes
ecological troubles in the 1960s and 1970s. Evidence of chemical
pollution in the Lakes and their tributaries now stretches back for
decades. In the 1960s Ohio’s Cuyahoga
River -- or more precisely a combination of oil,
chemicals, and trash floating atop it in Cleveland -- ignited and
smoldered, creating international headlines.
The Cuyahoga, and a TIME Magazine
cover story about the "death" of Lake Erie, helped focus public and
policymaker attention and inspire the first Earth Day events in
1970. New advocacy organizations such as the Lake Michigan
Federation, founded in 1970 by Lee Botts
brought new public pressure to bear. The first U.S. Clean Water Act
, signed by President
in 1972, was a key step
forward as was the innovative bi-national Great Lakes Water Quality
signed by Canada and the U.S. Thanks to a variety of
steps taken to reduce industrial and municipal pollution discharges
into the system, basic water quality had by the 1980s improved
sharply and Lake Erie in particular was significantly healthier.
The ongoing discharge of toxic substances has also been sharply
reduced thanks to federal and state bans of substances like
historic toxics remain embedded in harbor and rivermouth sediments
in dozens of "Great Lakes
Areas of Concern
The authoritative but now outdated 1972 book The Great Lakes:
An Environmental Atlas and Resource Book
noted that "only
pockets remain of the once large commercial fishery." In the
meanwhile however the great water quality improvements realized
during the 1970s and 1980s, combined with successful salmonid
stocking programs, have enabled the growth of a large recreational
Since the 1800s an estimated 160 species have invaded the Great
Lakes ecosystem, with ship ballast being a primary suspected
pathway, causing severe economic and ecological impacts. According
to the Inland Seas Education Association, on average a new invasive
species enters the Great Lakes every eight months.
One such infestation in the Great Lakes was the introduction of the
, which was first
discovered in 1988. The mollusk
efficient feeder, competing with native mussels
. It also reduces available food and spawning
grounds for fish. The zebra mussel also hurts utility and
manufacturing industries by clogging or blocking pipes. The
U.S. Fish and Wildlife Service
estimates that the economic impact of the zebra mussel will be
about $5 billion over the next decade.
alewife first entered the system west of
Ontario via 19th-century canals.
By the 1960s the
small silver fish had become a familiar nuisance to beachgoers
across lakes Michigan, Huron and Erie as periodic mass dieoffs
resulted in vast numbers of them washing up on shore; estimates by
various governments have placed the percentage of Lake Michigan's
biomass which was made up of alewives in the early 1960s as high as
90 percent. The various state and federal governments began
stocking several species of salmonids in the late 1960s, including
the native lake trout as well as non-native chinook and coho
salmon; by the 1980s alewife populations had dropped drastically.
Ironically, today the sharply lower numbers
of alewives is seen as a problem by those involved in the large recreational
fishing sector that has grown up particularly on Lake Michigan.
, a small percid
fish, became the most abundant fish species in
Lake Superior's St. Louis River
within five years of its detection in 1986. Its range, which has
expanded to Lake Huron, poses a significant threat to the lower
lake fishery. Five years after first being observed in the St.
Clair River, the round goby
can now be
found in all of the Great Lakes. The goby is considered undesirable
for several reasons: It preys upon bottom-feeding fish, overruns
optimal habitat, spawns multiple times a season, and can survive
poor water quality conditions.
Several species of water fleas
accidentally been introduced into the Great lakes such as Bythotrephes cederstroemi
having an effect on the zooplankton population. Several species of
have also been introduced that may
contend with native crayfish populations. More recently an electric
fence has been set up across the Chicago Sanitary and Ship
in order to keep several species of invasive Asian carps
out of the area. These fast-growing
planktivorous fish have heavily colonized the Mississippi and
Illinois river systems. 
It has been suggested that invasive species, particularly zebra and
quagga mussels, may be at least partially responsible for the
collapse of the deepwater demersal fish community in Lake Huron as
well as drastic unprecedented changes in the zooplankton community
of the lakeBarbiero R. P. et al. 2009. Recent shifts in the
crustacean zooplankton community of Lake Huron. Canadian Journal of
Fisheries and Aquatic Sciences 66: 816-828.
- LUHNA Chapter 6: Historical Landcover Changes in the Great
- See List of cities on the Great
Lakes for a complete list.
- Great Lakes Circle Tour.
- Stonehouse, Frederick (1985, 1998). Lake Superior’s
Shipwreck Coast, p. 267, Avery Color Studios, Gwinn, Michigan,
U.S.A. ISBN 0-932232-43-3,
- Matile, Roger. "Has a famed Great Lakes mystery been solved?"
Ledger-Sentinel, Oswego, Illinois. (2004).
- France claims historic Great Lakes wreck, Randy Boswell,
Canwest News Service, February 17, 2009
- Representative Phil English (PA03) - English
Praises Coast Guard’s Decision on Proposed Live Fire Zones
- Emanuel (Il05) - Press Release - Emanuel, Ehlers
Introduce Great Lakes Regional Collaboration Implementation
- Congress's attempt to dub Lake Champlain a 'Great
- " Does size matter? Lake St. Clair advocates believe
that it deserves to be called 'great'", The Plain Dealer, October
- " Great Lakes panel wants monster fish to stay
away", The Plain Dealer, October
- "Evolution of the Great Lakes Water Quality Agreement", Paul
Muldoon and Lee Botts, Michigan State University Press, 2005
- Baxter Bulletin - www.baxterbulletin.com
- Riley, S. C. et al. 2008. Deepwater demersal fish community
collapse in Lake Huron. Transactions of the American Fisheries
Society 137: 1879-1890
- Beltran, R. et al.. The Great Lakes: An
Environmental Atlas and Resource Book. (Washington &
Ottawa: United States Environmental Protection Agency and
Government of Canada, 1995, ISBN 0-662-23441-3).
- Cappel, Constance. editor, "Odawa Language and Legends: Andrew
J. Blackbird and Raymond Kiogima," Philadelphia: Xlibris,
- Cappel, Constance, "The Smallpox Genocide of the Odawa Tribe at
L'Arbre Croche, 1763: The History of a Native American People,"
Lewiston, NY: The Edwin Mellen Press, 2007.
- Dempsey, Dave On the Brink: The Great Lakes in the 21st
Century. (East Lansing: Michigan State University Press, 2004,
- George Cuthbertson authored
and illustrated “Freshwater, a history of the Great Lakes,”
(Toronto: MacMillan, 1931).
- Coon, W.F. and R.A. Sheets. Estimate of Ground Water in
Storage in the Great Lakes Basin, United States, 2006: National
Water Availability and Use Program [Scientific Investigations
Report 2006-5180]. Reston, VA: U.S. Department of the Interior,
U.S. Geological Survey, 2006.