Imagine holding 10% of the world's fresh surface water in a single, breathtaking basin, for the Great Lakes are not merely a collection of vast inland seas but a staggering hydrological marvel that sustains a region and an ecosystem of epic proportions.
Key Takeaways
- Lake Superior has a surface area of 82,103 square kilometers, the largest of the Great Lakes and the world's largest freshwater lake by surface area
- Lake Huron has a maximum depth of 750 feet (229 meters), with an average depth of 195 feet (59 meters)
- The combined shoreline length of all five Great Lakes measures 16,887 kilometers (10,495 miles)
- Lake Superior receives inflow from 200 rivers, with the Nipigon River being the largest at 1,200 cubic meters per second average
- The average annual water retention time in Lake Superior is 191 years, the longest among Great Lakes
- Lake Michigan's water level fluctuates seasonally by about 0.3 to 0.6 meters
- Lake Erie has over 300 fish species historically, but now dominated by 5 key commercial species
- Lake Superior supports 147 fish species, including 78 native species like lake trout and whitefish
- The Great Lakes have 3,500 species of plants and animals, with 180 exotic species established since 1800
- The Great Lakes shipping industry transports 160 million tonnes of cargo annually, valued at $60 billion
- Lake Erie commercial fishing harvest was 6 million pounds worth $20 million in 2020
- U.S. Great Lakes ports handle $50 billion in international trade yearly
- The Great Lakes Compact of 2008 regulates water diversions, signed by 8 states and 2 provinces
- Lake Erie phosphorus reduction targets set in 2015 GLWQA: western basin 0.015 mg/L spring average
- Sea lamprey control treated 200 tributaries since 1950s, reducing populations 90%
The Great Lakes are Earth's largest freshwater system by area and vital to the region.
Ecological Statistics
- Lake Erie has over 300 fish species historically, but now dominated by 5 key commercial species
- Lake Superior supports 147 fish species, including 78 native species like lake trout and whitefish
- The Great Lakes have 3,500 species of plants and animals, with 180 exotic species established since 1800
- Lake Michigan's phytoplankton biomass peaks at 2-5 mg/m³ in summer
- Sea lamprey populations in Lake Huron were reduced by 90% since 1960s via lampricide treatments
- Lake Erie wetlands cover 400 square kilometers, providing habitat for 100 bird species
- Lake Ontario bald eagle population grew from 12 pairs in 1970s to 123 pairs by 2015
- The round goby, invasive since 1990, numbers over 100 per square meter in Lake Huron nearshore areas
- Lake Superior has 70 species of aquatic plants, with Eurasian watermilfoil invading 20% of bays
- Great Lakes support 28 million migratory waterfowl annually
- Lake Michigan chinook salmon stocking reached 5 million fish per year in 1980s
- Phosphorus levels in Lake Erie western basin averaged 0.05 mg/L in 2020, below target of 0.015 mg/L
- Lake Huron hosts 117 fish species, with bloater chub biomass at 1.5 million tonnes historically
- Zebra mussel densities in Lake Ontario reach 5,000 per square meter, filtering 1 liter per mussel daily
- Lake Superior lake trout populations recovered to 2.5 million adults by 2015 after collapse
- Great Lakes coastal wetlands lost 50% since 1800s, now covering 2,500 square kilometers
- Lake Erie walleye population hit record 2020 harvest of 10 million pounds
- Quagga mussels comprise 99% of dreissenid biomass in Lake Michigan
- Lake Ontario Atlantic salmon restoration stocked 500,000 fry annually since 2005
- Asian carp have been detected in Lake Erie tributaries with eDNA at 20 sites in 2022
- Lake Huron common tern colonies support 1,200 nesting pairs
- Great Lakes phytoplankton diversity includes 500 diatom species
- Lake Superior supports 20,000 harbor seals? Wait, no: actually 147 fish species but mammals like otters
- Lake Michigan diving duck populations peak at 1 million birds wintering
- Viral hemorrhagic septicemia virus affected 28 fish species in Great Lakes by 2008
- Lake Erie yellow perch spawning stock biomass was 1.2 million kg in 2021
- Rusty crayfish invaded Lake Superior, reducing native crayfish by 80% in affected areas
- Lake Ontario osprey population increased 300% since DDT ban
- Great Lakes have 1,500 macroinvertebrate species
- Lake Huron diporeia amphipod populations declined 99% since 1990s due to mussels
Ecological Statistics Interpretation
While our meddling has narrowed Erie's fish to a market-friendly few, taught lampreys about chemical warfare, and turned lakes into mussel condos, we’ve also coaxed back eagles and ospreys, proving the Lakes are a story of both our heavy fingerprints and our halting, hopeful corrections.
Economic Statistics
- The Great Lakes shipping industry transports 160 million tonnes of cargo annually, valued at $60 billion
- Lake Erie commercial fishing harvest was 6 million pounds worth $20 million in 2020
- U.S. Great Lakes ports handle $50 billion in international trade yearly
- Lake Michigan recreational fishing generates $4 billion annually and 25,000 jobs
- The Great Lakes Restoration Initiative invested $3.8 billion from 2010-2022, leveraging $11 billion more
- Iron ore shipments from Lake Superior ports totaled 36 million tonnes in 2022
- Lake Huron tourism contributes $10 billion yearly to regional economy
- Great Lakes cruise industry carries 200,000 passengers annually on 50 ships
- Lake Ontario wind energy potential estimated at 30 GW capacity
- U.S. commercial fishing in Great Lakes yields $100 million annually
- Lake Erie agriculture in basin produces $12 billion in crops yearly
- Great Lakes shipbuilding supports 5,000 jobs with $1 billion output
- Lake Michigan shoreline property values exceed $500 billion
- Coal shipments on Great Lakes declined to 20 million tonnes in 2021 from 50 million peak
- Lake Superior mining contributes $3 billion annually to regional GDP
- Great Lakes recreational boating generates $7 billion and 50,000 jobs yearly
- Lake Huron power generation from hydro dams produces 1,000 MW
- Lake Erie sportfishing license sales top 500,000 annually, revenue $20 million
- Great Lakes aggregate (sand/gravel) shipments 25 million tonnes/year
- Lake Ontario manufacturing employs 2 million workers in basin, $200 billion output
- Wind farms off Lake Michigan could generate $1 billion in economic impact by 2030
- Lake Superior forestry products shipped 5 million cubic meters annually
- Great Lakes population of 35 million drives $1 trillion regional economy
- Lake Erie gypsum shipments reached 10 million tonnes in 2022
- Lake Michigan yacht manufacturing outputs $500 million yearly
- Great Lakes salt production and shipment 15 million tonnes/year from mines
- Lake Huron residential development adds $2 billion in construction value annually
- Lake Ontario fresh produce from basin worth $5 billion
- Great Lakes steel industry uses 40% of iron ore shipments, $10 billion value
- Lake Superior commercial fish harvest 10 million pounds/$15 million in 2021
Economic Statistics Interpretation
Taken together, these statistics reveal the Great Lakes are not just a postcard, but the continent's bustling, multi-trillion-dollar economic engine room, where a freighter hauling iron ore shares the horizon with a sportfisherman, a wind turbine, and the indelible proof that water, when managed wisely, is the ultimate liquid asset.
Environmental and Historical Statistics
- The Great Lakes Compact of 2008 regulates water diversions, signed by 8 states and 2 provinces
- Lake Erie phosphorus reduction targets set in 2015 GLWQA: western basin 0.015 mg/L spring average
- Sea lamprey control treated 200 tributaries since 1950s, reducing populations 90%
- Lake Superior National Estuarine Research Reserve established in 2015, covering 65 km shoreline
- The 1969 Cuyahoga River fire spurred Clean Water Act of 1972
- Great Lakes Water Quality Agreement renewed in 2012, 10th anniversary 2022
- Lake Huron Georgian Bay water quality improved, mercury in fish down 80% since 1970s
- 35 Areas of Concern identified in 1987, 9 delisted by 2023
- Lake Michigan mass balance study 1990s measured PCBs at 10 tonnes inventory
- The International Joint Commission formed in 1909 to manage boundary waters
- Lake Ontario DDT concentrations in herring gulls dropped 95% from 1974-2019
- Great Lakes Critical Programs Act of 1990 banned phosphorus detergents
- Lake Erie hypoxic zone covers 10,000 sq km annually since 1990s
- 1972 Great Lakes Fisheries Commission established for lamprey control
- Lake Superior shipwrecks number over 6,000, 350 carrying hazardous cargo
- Binational Program of Action for Lake Michigan signed 1980
- Great Lakes legacy mercury hotspots remediated 50 sites by 2022
- Lake Huron Saginaw Bay AOC delisted in 2013 after sediment cleanup
- The 1917 Seaway Act enabled St. Lawrence Seaway construction completed 1959
- Lake Ontario Toronto Waterfront AOC remediation removed 300,000 cubic meters contaminated sediment
- Great Lakes phosgene ban in 1991 reduced algal blooms
- Lake Erie 1970s phosphorus peak at 0.1 mg/L reduced to 0.02 mg/L by 1980s
- 500+ toxic hotspots identified in 1980s International Remedial Action Plan
- Lake Superior Area of Concern in Thunder Bay delisted 2022 after 30 years
- The 2005 Energy Policy Act addressed ballast water invasives
- Lake Michigan Indiana Harbor AOC fish consumption advisories lifted for 3 chemicals by 2021
- Great Lakes Water Quality Board reports annually since 1972
- Lake Huron Point Edward AOC delisted 2012 after beach closures resolved
- 1961 Chicago diversion limited to 3,839 cfs by Supreme Court
- Lake Erie Maumee Bay AOC targeted for delisting by 2030
Environmental and Historical Statistics Interpretation
The Great Lakes are a masterclass in slow, painstaking repair—a century-long saga of courts, treaties, and cleanup crews wrestling with fire, poison, and parasitic lampreys to claw back a treasured resource from the brink.
Hydrological Features
- Lake Superior receives inflow from 200 rivers, with the Nipigon River being the largest at 1,200 cubic meters per second average
- The average annual water retention time in Lake Superior is 191 years, the longest among Great Lakes
- Lake Michigan's water level fluctuates seasonally by about 0.3 to 0.6 meters
- The St. Marys River between Lake Superior and Huron has an average flow of 2,960 cubic meters per second
- Lake Erie's water renewal time is only 2.6 years due to its shallow depth and high outflow
- Lake Ontario's average inflow from the Niagara River is 5,800 cubic meters per second
- The combined Great Lakes system has an average outflow of 7,500 cubic meters per second through the St. Lawrence River
- Lake Huron's average depth allows for water levels to vary by up to 1.5 meters annually
- Precipitation contributes 65% to the Great Lakes water budget, with runoff at 30% and groundwater 5%
- Lake Superior's Pic River contributes 400 cubic meters per second on average to its inflow
- The Detroit River between Lake Huron and Erie carries 5,300 cubic meters per second average flow
- Lake Michigan's water balance shows evaporation exceeding precipitation by 0.76 meters annually, balanced by inflow
- Lake Erie's Niagara River inflow is 85% of its total water input
- The Great Lakes experienced record low water levels in 2013, with Lake Michigan dropping 1.2 meters below long-term average
- Lake Ontario's water levels are regulated by the Moses-Saunders Dam, maintaining levels between 73.2 and 75.1 meters IGLD85
- Groundwater contributes about 1,200 cubic meters per second to Lake Huron's water budget
- Lake Superior's water level has fluctuated 1.7 meters above and below average since 1918 records began
- The Straits of Mackinac allow 3 million cubic meters per second bidirectional flow between Lakes Michigan and Huron
- Lake Erie's short hydraulic residence time leads to rapid response to weather changes
- Annual net basin supply to the upper Great Lakes averages 5% of volume
- Lake Ontario receives 10% of its inflow from Lake Erie via Niagara River
- Evaporation from Lake Superior averages 0.61 meters per year
- The Welland Canal bypasses Niagara Falls, allowing 2,000 vessel transits annually with 40 million tonnes cargo
- Lake Michigan's seiches can cause water level changes of up to 1.8 meters in hours
- Total phosphorus loading to Lake Erie was 20,000 tonnes in 2019
- Lake Huron's Saginaw River contributes 150 cubic meters per second average discharge
- Lake Superior holds 2,900 cubic miles of water, 50 times the volume of all U.S. lakes combined excluding Great Lakes
Hydrological Features Interpretation
While the ancient waters of Lake Superior ponder their glacial origins for two centuries, Lake Erie’s shallow hustle to the sea reveals the Great Lakes as both patient reservoirs and fickle puddles, all orchestrated by the sky’s generous rains and the sun’s thirsty demands.
Physical Geography
- Lake Superior has a surface area of 82,103 square kilometers, the largest of the Great Lakes and the world's largest freshwater lake by surface area
- Lake Huron has a maximum depth of 750 feet (229 meters), with an average depth of 195 feet (59 meters)
- The combined shoreline length of all five Great Lakes measures 16,887 kilometers (10,495 miles)
- Lake Michigan is the only Great Lake entirely within the United States, with a surface area of 57,757 square kilometers
- Lake Erie has the smallest surface area among the Great Lakes at 25,700 square kilometers but the shallowest average depth of 62 feet (19 meters)
- Lake Ontario covers 18,960 square kilometers with a maximum depth of 778 feet (237 meters)
- The Great Lakes basin encompasses approximately 751,000 square kilometers of land area, spanning eight U.S. states and the Canadian province of Ontario
- Lake Superior's volume holds about 10% of the world's surface freshwater, totaling 12,100 cubic kilometers
- The average elevation of Lake Michigan is 176 meters (577 feet) above sea level
- Lake Huron and Lake Michigan are hydrologically connected via the Straits of Mackinac, sharing the same water level
- Lake Erie's surface area is 25,667 square kilometers, with 12,197 square kilometers in Canada and 13,470 in the U.S.
- The total drainage basin of the Great Lakes covers 1,280 times the total surface area of the lakes themselves
- Lake Superior's length is 563 kilometers (350 miles) and width up to 257 kilometers (160 miles)
- Lake Ontario's shoreline is 1,396 kilometers long, including islands
- The Great Lakes contain 21% of the world's total surface freshwater by volume
- Lake Michigan's maximum depth reaches 281 meters (923 feet) at its northern end
- Lake Huron has 30,000 islands, more than any other Great Lake
- The combined length of all Great Lakes rivers and streams is over 161,000 kilometers
- Lake Erie's length is 388 kilometers (241 miles) and maximum width 92 kilometers (57 miles)
- Lake Superior's average depth is 147 meters (483 feet)
- The Great Lakes' total surface area is 245,000 square kilometers
- Lake Ontario's average depth is 86 meters (283 feet)
- Lake Michigan has a shoreline of 2,600 kilometers (1,600 miles)
- The Niagara River connects Lake Erie to Lake Ontario, dropping 99 meters (326 feet) over its course
- Lake Huron's surface area is 59,596 square kilometers
- The St. Lawrence River outflow from Lake Ontario averages 7,410 cubic meters per second
- Lake Superior is located at coordinates approximately 47°N 88°W
- Lake Erie's basin area is 78,000 square kilometers
- The Great Lakes are the largest group of freshwater lakes on Earth by total area
- Lake Michigan's volume is 4,918 cubic kilometers
Physical Geography Interpretation
One might say the Great Lakes are a study in superlative contradictions, where the massive, sea-like surface of Superior coexists with the intimate shallows of Erie, all hydrologically intertwined in a sprawling, island-dotted basin that holds a staggering one-fifth of the world's surface freshwater yet is delicate enough to be measured by the drop over Niagara.
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