Like the proverbial canary in a coal mine, the tiny rainbow darter is a sentinel species for the Grand River which flows through Southwest Ontario and empties into Lake Erie.

The minnow's extreme sensitivity to pollution provides clear evidence of changes that are occurring more subtly through the river's aquatic food chain and, more broadly, throughout the Great Lakes watershed.

For several years, male darters living in the Grand River downstream from Kitchener-Waterloo had among the world's highest incidence of "inter-sex" characteristics, developing eggs in their testes. The phenomenon results from expsoure in the water to too much estrogen and other chemicals that interfere with reproductive development.

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But following the local municipality's $700-million upgrade of its sewage treatment plants two years ago, the percentage of darters displaying inter-sex characteristics declined dramatically, according to a team of biologists from the University of Waterloo who study the fish.

For senior researcher Mark Servos, that improvement is a welcome sign that degradation of Canada's waterways can be reversed with focused attention and investment in modern treatment facilities. But it cannot give rise to complacency, says the scientist, who holds a Canada Research Chair in water-quality protection at the University of Waterloo.

A University of Waterloo team member holds a male rainbow darter collected from the Grand River in Kitchener, Ontario on Saturday, November 7, 2015. The fish are extremely sensitivity to pollution and for years, male darters in the Grand River had among the world’s highest incidence of “inter-sex” characteristics, developing eggs in their testes. Peter Power/for The Globe and Mail

In addition to the estrogen, the researchers have identified a witch's brew of chemicals in the river, including phosphates from municipal sewers and farm runoff; antibiotics and other pharmaceuticals; and tiny bits of plastic which are appearing in growing quantity. The situation on the Grand River is emblematic of what is happening across the Great Lakes watershed. Prof. Servos said he believes drinking water quality is generally good in the Great Lakes watershed, but that there are concerns.



"There is no doubt that we have made progress in water management; things are way better than they were 30 years ago," he said in an interview on the Grand's east bank south of Highway 401, just before he and three doctoral students waded into the river to collect rainbow darters for their research. "But the consequences of not continuing to be vigilant and prioritizing water protection will be negative impacts on the health and prosperity of our communities."

The Great Lakes system provides drinking water to 44 million people – including nearly nine million Ontarians – and is home to commercial and recreational fisheries as well as environmentally important wetlands. A generation ago, the Great Lakes were in deep trouble as municipal sewage and industrial toxins were causing serious contamination, particularly in Huron, Erie and Ontario where population and industry was most concentrated.

In its most recent report on the health of the Great Lakes, the International Joint Commission reported substantial progress but also persistent and emerging problems. Concentrations of such carcinogens as dioxins and benzenes are down 90 per cent from the 1970s, though progress in many cases has stalled. Fish populations are healthier, though numerous advisories limiting fish consumption remain in place on all the lakes. Mercury levels fell between 1970 and 1990 but have stabilized since the mid-1990s, according to the IJC, the bi-national commission that manages water-quality issues in the lakes.

Now the largest freshwater habitat on Earth faces new threats. A plethora of chemicals is making its way into the lakes, including new nano-particles whose impact on the environment and human health is unknown, and pharmaceuticals, including antibiotics.

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The overload of such nutrients as phosphorus and nitrogen is causing toxic algae blooms in numerous locations, particularly in the warm, shallow western basin of Lake Erie. Last year, the city of Toledo, Ohio, which lies on the lake's western shore, had to shut down its water intake for several days due to the algae which also fouls beaches on the Ontario shoreline.

The IJC says the algal blooms are the result of increased fertilizer runoff from farms and overflow from municipal sewers, as well as the warming of the lakes caused by climate change. The Ontario and federal governments have joined with the Great Lakes states in an effort to cut nutrient pollution by 40 per cent, in part by working with farmers to improve land-use practices.

Treated sewage flows into the Grand River from the Hespeler Water Treatment in Waterloo, Ontario on Saturday, November 7, 2015. Two years ago, Kitchener-Waterloo completed a $700-million upgrade of its sewage treatment plants and researcher has subsequently identified improvement in the Grand River habitat. Peter Power/for The Globe and Mail

The IJC's Canadian chair, Gordon Walker, said there are "grave concerns" about the blue-green algae that is showing up in waterways across North America, and has been particularly bad in Lake Erie, in Lake of the Woods that straddles the Manitoba-Ontario-Minnesota border, and in Lake Winnipeg.



The IJC has also pointed to the chemicals that are being flushed into the rivers and lakes, and that traditional municipal waste-water treatment does not capture. When Mr. Walker served his first term on the IJC 20 years ago, there were 250 identified chemicals; today, there are 650.

"Most of these are not taken out by the normal means of sanitary treatment," he said. "So far as we know, the water we all drink is treated and treated well and we do not have concerns. But we sometimes wonder if 30 years later, after they've been in the environment that long, [the chemicals] may prove to be a problem."

Veteran water consultant Ralph Pentland co-authored the 2013 book, Down the Drain: How We are Failing to Protect our Water Resources, which argues that governments have to do a better job regulating the chemicals that are introduced into the consumer society and then end up in the water supply.

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He complained that the protection of the Great Lakes often falls victim to jurisdictional wrangling among federal, provincial and municipal governments. Mr. Pentland is a member of the Forum for Leadership on Water, which released an open letter during the recent federal election on the need for better protection of Canada's fresh-water resources.

The group urged the federal government to reinvest in the science of water quality and protection; to modernize its policies and legislation; and to make long-term investment in infrastructure that will provide resilience from extreme storms. Mr. Pentland said federal and provincial governments may have to look at "market mechanisms" – some type of pricing regime – to provide greater protection to the Great Lakes and other bodies of water.

"We don't adhere to a polluter-plays principle at all in this country," he said. Water use "is a free good provided by society as a whole. We all pay for the damages."

Illustrations: Trish McAlaster/The Globe and Mail

Microplastics in Toronto's Humber Bay, Lake Ontario



The bay at the mouth of the Humber River on Lake Ontario is considered a hot spot for "microplastics" – tiny bits of plastic that accumulate in the water, along the banks and in sediment. The plastic particles that are less than five millimetres in size and come from a variety of sources, including cosmetics and toothpaste, clothing and industrial processes.

University of Western Ontario geologist Patricia Corcoran has scoured the shoreline with her graduate students and found a high concentration of pellets, even floating in the Humber River, which flows through heavily industrialized areas of the Greater Toronto Area.



Legislators in the United States and Canada are working to ban microbeads – a subset of microplastics that are used as abrasives in cosmetics and toothpaste – though the laws are often riddled with loopholes. Dealing with microplastics as a whole is a bigger challenge, and requires society-wide effort to reduce use and find better alternatives for disposal.

Illustrations: Trish McAlaster/The Globe and Mail

Blue-green algae near Pelee Island, Ont., Lake Erie

Municipals officials for the past two years have had to issue advisories and in some cases close beaches due to the presence of toxic blue-green algae bloom in western Lake Erie. In 2014, the city of Toledo, Ohio, had to close its water intake for several days due to the algae, and issue an advisory not to drink water from the lake.

The troublesome algal growth results from high levels of nutrients from municipal sewers and in the runoff that flows directly into the lake and its feeder rivers. The problem is acute in the shallow western basin of Lake Erie. The growth is accelerated by the warming of the Great Lakes over the past three decades and the sharp decline in the number of days they are covered with ice.



The intensive cultivation of corn in Great Lakes states and Ontario to supply the ethanol industry has been a significant factor in the algae problem, said Raj Bejankiwar, a scientist at the International Joint Commission, which oversees water-quality issues on boundary waterways. Governments around the lakes have agreed on plans to reduce nutrient runoff, including working with farmers to fine-tune their fertilizing practices.

Illustrations: Trish McAlaster/The Globe and Mail

Fish kill at a nuclear plant near Kincardine, Lake Huron

Bruce Power's nuclear plant on the shores of Lake Huron has been cited under the Fisheries Act for doing "serious harm" to whitefish populations, which are killed by the intake and discharge of water into the lake. The Canadian Nuclear Safety Commission says the Bruce plant does not constitute a threat to the lake's overall fish population, but local aboriginal communities and environmentalists disagree.

As required under the Fisheries Act, Bruce Power is now working with the Saugeen Ojibway Nation to assess the plant's impact on the band's commercial fishing operation and look to potential mitigation techniques. Bruce has applied under the act for licence to kill millions of fish.



Environmentalists and some local residents also worry about Ontario Power Generation's plan to build a nuclear waste repository deep underground, just a kilometre from the Lake Huron shore. The panel comprising the Canadian Environmental Assessment Agency and the Canadian Nuclear Safety Commission has concluded the deep geological repository does not pose an undue threat to the lake, but critics – and several U.S. politicians – argue any risk to the Great Lakes in unacceptable. The federal Liberal government last week delayed a final decision on the repository until March 1.

Illustrations: Trish McAlaster/The Globe and Mail

Dead zone near Green Bay, Wis., Lake Michigan

In Lake Michigan's Green Bay, municipal, industrial and farm runoff is causing a growing dead zone, in which algae consumes virtually all the oxygen necessary for aquatic life.

Local environmentalists point to the proliferation of industrial dairies in Kewaunee County as a contributing factor due to leaks and storm runoff from manure ponds. They have also raised concerns about liquid manure spread on fields as fertilizer, contaminating drinking-water wells.



Citizens in Kewaunee County have petitioned the U.S. Environmental Protection Agency to investigate the contamination of ground water and force state regulators to act.

Illustrations: Trish McAlaster/The Globe and Mail

Mercury pollution in Thunder Bay's North Harbour, Lake Superior

The city's north harbour contained some 400,000 square metres of contaminated sediment with elevated levels of mercury and other industrial pollutants from a former paper mill. Reclamation of the site is one of the International Joint Commission's requirements to remove the Thunder Bay waterfront from its list of "areas of concern."

The area provides habitat for perch, walleye, northern pike and a host of smaller fish, and consultants' reports say it could be reclaimed as a recreational fishing spot if it was remediated.



EcoSuperior, a local environmental group, has worked with consultants and government scientists to document the extent of the problem and propose a cleanup. "This work was completed last March, and there has been no word from any level of government as to whether or not any remediation efforts will be initiated," said EcoSuperior's executive director, Ellen Mortfield.

Also from the series:

Reduced federal oversight leaves a critical resource exposed It powers industry and is the lifeblood of healthy communities. But years of reduced federal oversight have left the government with major decisions about managing a resource we take for granted