Globe and Mail
WHEATLEY HARBOUR, ONT. -- On June 22, 1969, the
Cuyahoga River did something rivers are not supposed
to do. It caught fire. Flames burst out along several
kilometres of the oil-coated waterway where it flows
through Cleveland's gritty industrial heartland
Erie. Embarrassed municipal
authorities dispatched three fire battalions plus
a pumper boat, the Anthony J. Celebrezze, to knock
out the blaze, which raged five storeys high and
damaged two key rail bridges.
The Cuyahoga had burned before but this time the
news that pollution could make a river flammable
caught the public's imagination. The incident became
a global symbol of environmental degradation, and
scientists started to look closely at what dozens
of dirty rivers were doing to Lake
Erie, the most southerly
of Champlain's five "sweetwater seas."
To the amazement of people in Canada and the United
States, they discovered that Erie
was dying. Stinking masses of algae and rotting
seaweed had turned its once-azure water a murky
green; every summer, so much of the lake was being
depleted of oxygen that a terrifying dead zone was
forming on the bottom.
Spurred to action, government and industry spent
billions on pollution controls, upgrading sewage-treatment
plants at big U.S. cities such as Detroit and Cleveland,
and sparked an environmental renaissance. By the
mid-1990s, the lake was being held up as proof that
environmental degradation can be overcome. It was
deemed to be cleaner than it had been in 50 years,
and many of those responsible for its recovery moved
But there was a problem with Lake
Erie's return from
the brink. It didn't last.
Erie is in serious
trouble. The dead zone is growing again, and the
floating mats of smelly algae are back, along with
a blue-green variety that is toxic. As in the 1960s,
a vicious strain of avian botulism is claiming thousands
of the birds that feed on Erie's
fish, and chemical toxins are building up in the
fish and fowl.
The walleye -- the top fish in the lake's food
chain -- is also in trouble. Prized for its tasty
white flesh, the species has undergone a dramatic
population crash in Lake
Erie, from about 100
million in 1988 to less than one-third of that two
years ago. And while the cleaned-up Cuyahoga no
longer catches fire, fish in parts of the river
suffer from persistent and mysterious tumours.
Nobody really knows what is causing all this, except
that "we declared victory too soon," admits
David Dolan, a professor of applied science at the
University of Wisconsin at Green Bay who tracks
phosphorus pollution for the U.S. Environmental
Protection Agency. "We let our guard down. It
So a huge EPA-financed team of Canadian and U.S.
researchers has attacked a body of water almost
five times the size of Prince Edward Island this
year in search of clues. The theories range from
global warming to the possibility that zebra mussels
and other alien species from the Black Sea have
so altered the ecology that all the old scientific
rules no longer apply.
The situation is critical because Erie
acts as a kind of sentinel for the rest of the Great
Lakes, the world's largest body of fresh water.
Bad things usually show up first on the shallowest
and warmest of the big lakes because Erie
has far more aquatic life and far less water than
In fact, the renewed algae blooms plaguing Erie
have already begun to crop up elsewhere -- on "Lake
Ontario and I've heard reports from Lake
Michigan," says Ralph Smith, a biologist at
the University of Waterloo.
He warns that "we can definitely point to quite
a few trends that are reversing, things moving back
in the wrong direction, the algae, the fouling of
the beaches. It's not just a one-summer peculiarity.
It's happening too regularly."
Mr. Smith says his research vessel often stalls,
sometimes 10 kilometres from shore, when clumps
of algae clog its propellers, and he predicts that
people who like to think of Erie
as relatively clean are in for a shock. "The
amenity value of the lake is at peril right now.
I'd hate to be a shoreline property owner. I'd be
Of all the problems, the dead zone alarms researchers
most. It is a wide portion of the lake's central
basin between Cleveland and Port Stanley on the
Ontario shore where in summer the deeper water suffers
from anoxia -- it's almost devoid of oxygen and
thus lethal to aquatic life. Any fish that swims
to the depths and lingers too long suffocates.
Researchers thought this problem had been solved
by the controls on phosphorus imposed in the 1970s,
but water samples taken from the basin last year
showed that its oxygen content had declined more
rapidly than anything seen in almost 10 years.
Some scientists believe that the central basin
may have always had a small dead zone simply because
of the way water in large lakes tends to form layers
based on heat. Winter turbulence means than in spring
water is pretty much a uniform temperature, with
oxygen content identical from top to bottom. But
once the surface begins to warm in the summer, the
lake's water column divides into two.
Being less dense, warm water rises to the top and
sits on the heavier, colder water. The two become
as distinct as layers in a cake, with the surface
water always exposed to air, but because it doesn't
mix with what's below, oxygen at the bottom isn't
replenished. Whatever is there when the lake stratifies
in spring has to last until early fall when surface
cooling restores the lake's uniform temperature.
Only then do the layers merge, permitting wind and
wave action to drive fresh oxygen to the bottom.
The part of the basin that runs out of oxygen is
"always here," says Tim Johnson, who is
in charge of Erie
research for the Ontario Ministry of Natural Resources,
"but suddenly it seems to be growing worse.
That was the part that puzzled us."
Surface water in spring can have as much as 12
parts of oxygen per million while readings in the
dead zone have plunged to 1 ppm -- one-quarter of
the amount that leaves big fish such as salmon and
lake trout highly stressed. Anything less and they
may as well be on life support.
Phosphorus is the key nutrient that controls the
lake's ecosystem -- in excessive amounts, it's like
a steroid to algae, driving growth out of control.
When algae dies, it sinks to the bottom and rots,
depleting the water of oxygen.
In the early 1970s, scientists believed that slashing
the phosphorus pollution would make the dead zone
disappear. Canadian and U.S. governments set their
sights on allowing only 11,000 tonnes into the lake
every year, versus almost nearly 30,000 tonnes in
the sixties. They reached their target in the early
eighties, thanks to bans on phosphates in detergent
and improved sewage treatment.
Since then, the annual figure has varied, but has
generally stayed under the limit, at least according
to official records -- about 9,000 tonnes in 2000
and only 7,000 tonnes a year earlier. And still
the dead zone continues to grow, which leaves scientists
scratching their heads.
"We kind of hoped this oxygen depletion would
be a lot, lot better by now," concedes Murray
Charlton, a researcher at Environment Canada.
Mr. Johnson of the MNR is equally perplexed. The
arrival of the zebra mussel in the 1980s altered
the way phosphorus is distributed in the lake, he
says, but concentrations of the pesky mollusk have
stayed much the same in recent years. "Phosphorus
loadings haven't changed, mussel densities haven't
changed diametrically, and so why now," he wonders,
"is the lake suddenly changing, reverting back
to more of a 1970s state?"
Suspicion has fallen upon the official figures
-- should they be so rosy? Perhaps not. They are
based on estimates and voluntary reporting by polluters,
and even Mr. Dolan, who tracks the data for the
EPA, questions their reliability.
The task is further complicated by the fact that,
Erie looked so healthy
10 years ago, scientists dismantled much of its
pollution monitoring. Thinking Erie
had been saved and facing major government budget
cuts, they assumed money could safely go to more
pressing problems. Now, only eight instead of all
30 major rivers running in the lake are monitored,
even though they carry most of the fertilizer runoff
from farms, the single biggest source of phosphorus.
Farmers face no restrictions on its use even though
it is so soluable in water that anything not immediately
absorbed by plants is washed from a field by the
Spending cuts also have reduced the number of spot
checks conducted to verify the emission claims of
sewage-treatment plants, which Mr. Dolan says are
running out of capacity because of population growth
and suburban sprawl. To make matters worse, major
U.S. cities such as Detroit have antiquated systems
that carry human waste and storm water in the same
pipes. This approach doesn't cause extra pollution
-- as long as it never rains.
"The sewage treatment plants are at their capacity
and it doesn't take much of a rain, a half-inch
or a quarter-inch, and they're already overflowing,"
Mr. Dolan says. "What you'd like to see is them
handle at least a moderate rain before overflow
He tries to account for how much untreated phosphorus
this generates, but the calculation is imprecise.
"I'm concerned that if trends continue, I won't
be able to make a credible estimate at all. I know
I'm under-reporting," he says but he is "probably
missing 10 per cent at worst."
Dealing with the phosphorus problem this time promises
to be difficult. Back in the 1970s, the cleanup
meant upgrading a few dozen highly visible sewage-treatment
plants and industrial polluters. Any reductions
now will require weaning tens of thousands of farmers
in the lake's watershed off the synthetic fertilizers
they've come to rely on.
According to Mr. Dolan, voluntary appeals have
been tried and just don't work. There has to be
a strict limit on fertilizer use or producers have
to make a mass switch to sustainable farming. "Until
they actually regulate it, I don't think you're
going to see appreciable changes. People are concerned
about the yield of their crops, and phosphorus is
the short track to increasing their yields."
Global warming also may play a role in the burgeoning
Municipal intake pipes that draw supplies from
the lake have shown a consistent increase in temperatures
since the early 1960s. This added warmth may be
extending the period that Erie
is stratified every year, forcing the deep zone
to subsist even longer on its springtime oxygen
Warming also dries up the lake, lowering water
levels in each of the past three years. The central
basin is typically about 22 metres deep, with the
dead zone occupying the bottom two or three metres.
A thinner water column could lead to a thinner cold-water
zone at the bottom and a smaller reservoir of oxygen.
Scientists realize there is nothing they can do
about global warming, but they aren't convinced
that either climate change or phosphorus is the
only culprit. Some believe that much of the blame
belongs to two tiny foreign invaders: the thumbnail-sized
zebra mussel and its relative, the quagga mussel.
When they arrived, most likely in bilge water dumped
by an ocean-going tanker, they were viewed as just
a nuisance that clogged water pipes and cut swimmers'
feet. But they had one beneficial effect, at least
from the human perspective. By filtering out the
microscopic algae they like to dine on, they made
water much clearer.
But now some scientists speculate that the mussels
are far more pernicious, causing not only the dead
zone, but the renewed growth of toxic algae, avian
botulism and toxic chemical contamination of wildlife.
They grow in dense mats -- thousands per square
metre -- on the lake bottom not far off shore. Mr.
Smith, the Waterloo biologist, is trying to determine
whether they have become so numerous that, between
the food they draw to the bottom and the waste they
generate, their presence is what's robbing the water
of oxygen. "The possibility is that they are
moving a lot of organic particles into the deep
zone of the lake," he says. "An obvious
candidate would be the fecal material of the mussels
By depleting the oxygen, the mussels also may be
creating an ideal habitat for botulism, which is
caused by Clostridium botulinum,a nasty bacterium
that thrives in oxygen-starved waters. Environment
Canada biologist Jeff Robinson warns that "this
is a working theory -- at this point, we haven't
proven it," but the bacterium is a natural part
ecosystem and usually hasn't been much of a problem.
"Traditionally . . . conditions would very rarely
come together to allow this botulism toxin to move
up through the food chain," he explains.
So, something has happened to allow it to kill
off thousands of waterfowl along the Lake
Erie coastline since
1999, including, scientists suspect, a major attack
this year near Long Point, Ont. As well, the disease
has attacked birds on Lake
Ontario and on the Canadian side of Lake
Huron, wiping out loons around Grand Bend.
How does a disease created on the bottom reach
birds on the surface? Researchers have begun to
suspect that another newcomer -- the round gobi
-- plays a major role. A bottom dweller first seen
in 1993, it is now among the lake's more abundant
fish. It preys upon its fellow Black Sea natives,
the mussels, and in turn is a favourite food of
mergansers and other waterfowl, which may be how
they contract the botulism.
The end result, says Mr. Robinson, who is recording
the death toll for the Canadian Wildlife Service,
isn't for the faint of heart. "It's pretty disturbing
to see large numbers of [dead] fish and sick and
Margrit Kapler agrees. She has a cottage at Point
Ryerse, just west of Port Dover, Ont., and has been
a happy neighbour of Erie
for 30 years. But on the Labour Day weekend, she
was shocked to see hundreds of dead fish and birds
start to wash up on her beach. Worried by the smell,
she began to bury the carcasses but found she couldn't
keep up. It turned into a long weekend of death
on the beach. "I have never seen anything like
that," she says.
As well as botulism, the zebra mussel is linked
to renewed outbreaks of cyanobacteria, the toxic
blue-green algae that produced huge "blooms"
at the western end of the lake until the 1970s phosphorus-abatement
program. Suddenly, in 1998, it made a major comeback
and this summer, after laying low for three years,
came back yet again.
The blooms can kill people, although the Great
Lakes region has no known victims, and their return
may be due to excessive farm fertilizer. Or it may
be because zebra mussels feed on the algae but spit
out the cyanobacteria, in the process helping them
thrive while eliminating many competitors.
Higher on the food chain, the picture looks no brighter.
In August, fisheries researchers from Ontario,
Ohio and Michigan conducted their annual trawl of
the lake in search of young walleye that were born
this spring. "We didn't find any," says
John Cooper of the Ontario Ministry of Natural Resources.
"We've never seen it this bad before."
The walleye may have had a difficult spawn because
the spring was so cool. But the fish also prefers
murky water -- its eyes have adapted to feed in
low-light conditions -- and the zebra mussel is
too clear for them.
Jolted by the decline, Ontario and state governments
bordering the lake have have cut fishing limits
in half to see if stocks can be rebuilt.
The walleye is important because it is what's called
a keystone species. Just as a keystone supports
all the bricks in an archway, an ecosystem's keystone
creature stabilizes the entire community. If the
walleye is in trouble, fish it preys upon -- smelts,
for example -- may run riot, taking over the lake,
as they did in the 1960s.
Erie in such dire straits,
what can be done to help it?
In the 1960s, when scientists discovered that phosphorus
was such a problem, there was a sense of confidence.
The solution was simple: Reduce the amount of chemical
reaching it, and Erie
Now, the researchers are far less certain. They
consider the challenges the lake faces to be far
more daunting -- perhaps even unfixable.
Roger Knight, supervisor of Ohio's Sandusky Fisheries
Station, has studied Erie
for 20 years and still considers it "a much
better lake than it was in the sixties and early
But he worries about the impact of the alien species
and feels these exotic "bad guys" are causing
an "unprecedented level of change" and "now
dominate a large part of the community."
He says biological pollution is more difficult
to counteract than other environmental threats.
If chemicals are a problem, levels can be reduced
or a product banned altogether. Not so with a round
goby or zebra mussel, whose prodigious breeding
overwhelm any control efforts. "There is nothing
you can do to eliminate these unwanted guests,"
Mr. Knight says.
Hugh MacIsaac, a biologist with the University
of Windsor's Great Lakes Institute, also worries
that the foreign species, coupled with climate change
and all the toxic chemicals, may pose a threat far
greater than that of the 1960s. "We have problems
that are at least as pressing, and even maybe more
pressing than some of the ones that we thought we
had solved," he explains.
The MNR's Mr. Johnson warns that Erie,
although cleaner than before, is in an "extreme
state of turbulence." Based at the ministry's
fisheries station, a collection of metal-clad buildings
at Wheatley Harbour, he works within a few feet
of the trouble lake and says that all he knows about
the answers to its problems is that they won't be
"The more time I spend here," he says,
"the more I realize the true depth and breadth
and complexity of the issues."
Martin Mittelstaedt writes on the environment
for The Globe and Mail.
by the numbers
Length: 388 kilometres
Width: 92 kilometres
Average depth: 19 metres
Maximum depth: 64 metres
Volume: 483 cubic kilometres -- *fifth among
Shoreline: 1,402 kilometres (including islands)
Surface area: 25,655 square kilometres --
*fourth among Great Lakes
Age: 14,000 years since last glacier, 4,000
years in present form
Neighbouring population: 10.5 million U.S.
and 1.9 million Canada
Ontario has a smaller surface area, but holds more
than three times as much water.