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North America couldn’t survive without the Great Lakes. They power the economy, quench inhabitants’ thirst and provide an array of ecosystem services. Together, Lakes Huron, Ontario, Michigan, Erie and Superior contain 95 per cent of the continent’s fresh surface water.

With the 1959 opening of the St. Lawrence Seaway linking Montreal’s ports to Lake Ontario, the lakes opened to the rest of the globe. Today, annual shipping exceeds 200 million net tonnes; almost a quarter of that travels to and from overseas ports.

As a result, the region is now the world’s fourth-largest economy. With a GDP of $4.7 trillion, the Great Lakes account for 28 per cent of combined Canadian and U.S. economic activity, according to a 2013 report from BMO Nesbitt Burns. Manufacturing is the top industry.

That makes the region particularly vulnerable to global economic volatility, but it also faces a more insidious risk: climate change. The symptoms – low water levels, extreme weather conditions and invasive species – threaten not only the Great Lakes, but also its businesses and people.

Lower lakes, lower revenues

Huron and Michigan’s levels have been below average for the past 14 years, and in January 2013 both lakes reached record lows. Ontario, Erie and Superior also face persistent low levels.

Gail Krantzberg, professor of civil engineering at McMaster University in Hamilton, Ontario, says climate change is part of the reason. “There’s less ice cover in winter, and you get evaporation in the winter months that is not compensated for by [rain] in the summer months. You also get snow packs that melt in the middle of winter, so there’s no spring meltwater, and that lowers levels even more.”

These conditions “are a direct threat to manufacturing in the Great Lakes,” says Ed Wolking, president of the Great Lakes Manufacturing Council in Detroit. He says they also challenge the $33.5 billion commercial navigation industry.

That’s because there is now less clearance at key transit points on the lakes, forcing ships to reduce the amount of cargo they carry. This is concerning in part because shipping is more fuel-efficient than rail and truck delivery per tonne of cargo.

The Lake Carriers’ Association (LCA) estimates for every inch of water drop, its 57 ships have to leave behind 8,000 tonnes of cargo – enough iron ore to produce steel for 6,000 cars. What’s more, “Vessels are reducing loads by an average of 15 per cent per trip to avoid scraping the bottoms of harbours and channels,” says the LCA.

Wolking adds, “A ship that would make 50 trips a year would incur extra costs of $2 million a year from operating at a depth shortfall of 24 inches. Consumers and manufacturers will pay for it in the end.”

Manufacturing operations also suffer. “If a [factory] has a near-shore water intake, [it could be] high and dry now,” says Stephen Carpenter, director of the Center for Limnology (a term for freshwater science) at the University of Wisconsin. “They’d have to build the pipe out further or deeper, and that costs money.”

Lower lake levels also threaten local tourism, which rakes in $12 billion annually, and fisheries, a $7 billion industry. A consortium of Georgian Bay mayors in Ontario says cottagers will have to spend $500 million to extend and repair docks and water systems. Marinas have to dig up sediment, or dredge, to maintain enough clearance for boats. And businesses that rely on a thriving waterfront suffer when harbours dry up.

Commercial and recreational fishers can’t go as close to shore as they used to, which reduces the types and number of fish they can catch. Those who risk it can damage their boats when bottoms hit shore.

Flooding the supply

Not only are the Great Lakes now chronically low, but when rainfall comes, too much comes down on water systems too quickly. In June 2012, about 10 inches of rain fell over northeastern Minnesota in less than 24 hours, causing more than $100 million in damage. Then, in July 2013, a record-breaking five inches fell on Toronto in seven hours, cutting power to 500,000 people.

According to reinsurer Munich Re, such extreme weather events aren’t going away. From 1980 to 2011, they became more frequent in the United States. Such storms cause massive flooding, and are exacerbated in major cities because asphalt surfaces don’t absorb water. Instead, rain must flow into storm drains, further overwhelming infrastructure. “That releases sewage back into the lakes,” says Krantzberg. “There’s economic burden for municipalities, households, businesses and insurance companies when basements get backed up with sewage, for example, or when entire bridges get washed away.”

And in rural areas, heavy rains wash soil and fertilizer into lakes. Trouble is, that runoff includes phosphorus, which boosts algal growth. Too much algae clogs water intakes, imbalances fish populations and irritates people’s skin. That drives away tourists, and challenges recreational and commercial fishers.

“Storm events are going to transport more nutrients into the lakes and lead to more algal bloom, coastal pollution and water quality problems,” says Carpenter. “That means the water drawn needs to be [more heavily] treated, which is expensive.”

In 2011, Lake Erie experienced its worst bloom in decades – it covered a fifth of the lake. Boats had to slow down when driving through the toxic, neon-green scum, reports news service EcoWatch.

Unwelcome guests

Climate change and carelessness have caused more than 180 non-native species to settle in the Great Lakes. “As the lakes warm, some species that couldn’t handle the deep cold waters now can,” says Krantzberg. And as global trade increases, so do the number of international ships and the number of foreign species hitching rides.

These species have caused declines in almost 46 per cent of local endangered plants and animals. One invader, the common reed, has grown so densely on shorelines that birds can’t nest and fish can’t move, says Mary Muter, chair of Sierra Club Ontario’s Great Lakes section.

And invasive fish and animals disrupt the food chain, meaning native species may not get enough to eat. Recreational and commercial fisheries suffer if their usual catch disappears.

“Salmon are valuable both for sport and commercial fishing, but the entire [Chinook salmon] fishery is now dwindling” in Lake Huron, says Carpenter. “To some extent that’s being replaced by inshore fishing of walleye and yellow perch, but that means the industry [has to] retool.”

Invaders can also cause problems for municipalities and manufacturers. Zebra mussels arrived in Lake St. Clair in the late 1980s via transoceanic ships. The crustaceans like to colonize intake pipes, clogging them. Controlling this costs $250 million each year, according to the University of Wisconsin. Worse, the U.S. Geological Survey estimates the mussels cause “billions in damage annually to boats, docks, hydroelectric systems and other vital infrastructure.”

And scientists are concerned about a potential invader: Asian carp. The carp make up 95 per cent of fish in some parts of the Illinois and Mississippi Rivers. They breed quickly and eat voraciously. Silver carp can leap as high as 10 feet out of the water when disturbed, damaging property and injuring people.

The carp haven’t yet reproduced in the Great Lakes system, but if they do, they could devastate native fish populations, and thus the combined $23 billion fishing and recreation boating industries. Recognizing that, in 2002 the U.S. Army Corps of Engineers built electronic barriers in the Chicago Area Waterway System to prevent migration of the carp from the Mississippi River to Lake Michigan.

Such initiatives aren’t cheap. The barrier cost $9 million to erect and $47 million to maintain in 2011. In total, the U.S. government has invested more than $200 million over four years in anti-carp measures. As part of that, in July 2013, the government will spend $51.2 million to upgrade existing barriers and construct new ones.

Completely dividing the two waterways could cost up to $9.5 billion, finds a 2012 report from the Great Lakes Commission and the Great Lakes and St. Lawrence Cities Initiative.

Solutions: mitigation, adaptation

The threats facing the Great Lakes magnify each other, so mitigation requires broad action. Slowing climate change should be an industry priority, says Carpenter. “Their livelihoods depend on the climate, so they should be activists in climate improvement.”

He recommends removing U.S. and Canadian biofuel subsidies. “It’s driven a huge increase in corn acreage, which is the most harmful crop for water quality,” he says. “Corn is not good at intercepting runoff, and the land sits vacant for nine months of the year. There’s a short line between the subsidy and harm to water resources.”

Agriculture can also stem fertilizer runoff to help reduce algal bloom. “Increase the amount of cover by year-round vegetation so we don’t have a lot of bare soil,” he suggests. “Use less phosphorus fertilizer.”

Saad Jasim, an environmental consultant and former director with the International Joint Commission (IJC), agrees. “If you used to put fertilizer down in September, but now the heavy rains come in September, wait another month because you don’t want to waste money,” he says.

Improving infrastructure can also help reduce severe storm damage and prevent sewage from getting into the lakes. “Our wastewater infrastructure isn’t designed for the 100-year storm, which is now happening a few times a year,” says Krantzberg. She says to adapt, municipalities should upsize pipes when it’s time for repairs. Cities can also redevelop brownfields and leave greenfields to absorb rainwater.

To compensate for impervious city surfaces, Krantzberg says local businesses can “use porous pavement, [construct] green roofs and put bioswales [grassy gutters that let water percolate down] on the sides of parking lots.”

Industry players should also track and manage their water impact. The Council of Great Lakes Industries is creating a region-specific water footprinting tool based on the Alliance for Water Stewardship model and set to launch in 2014.

To prevent new invaders, ships must follow water intake and discharge regulations. Ships are required to: take on water when floating high to avoid sucking bottom-feeders, minimize the amount of water drawn, treat water prior to discharge, and only discharge in designated areas.

To combat low lake levels, many industries have advocated dredging. But it can displace marine life and disrupt water flows. “From an environmental perspective, dredging is a pretty horrible activity,” says Muter.

Instead, she applauds the IJC’s April 2013 recommendation to install flow-reduction sills in the St. Clair River, saying the structures would both increase lake levels and protect fish habitats over the long term. The IJC proposed raising levels by 10 inches; Muter would prefer 20 inches. She adds there’s an outstanding agreement between the U.S. and Canada for 16 inches.

Sills, which are like speed bumps, would hold water back on Lake Huron. Muter estimates it would cost about $200 million. “It will take three years for the U.S. Army Corps of Engineers to come up with the analysis,” she says, and another year for governments to agree to and fund the project. “Within 10 years the water levels in Michigan, Huron and Georgian Bay can be restored.”

While some stakeholders may not be able to wait, Muter says that’s the “harsh reality when dealing with bi-national waters.” Plus, dredging can literally only go so far. If you install sills responsibly, she says, “you protect all Great Lakes and deal with 100 years of human alterations in the St. Clair.”

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