Tom Spears
The Ottawa Citizen
November 2, 1998

The giant Moses-Saunders hydro dam across the St. Lawrence River is destroying fish habitat and indirectly tainting the fish, says a major study by the University of Ottawa.

The river is cleaner than it used to be, and cleaner than most people who live near it realize, the University of Ottawa study found.

But the Moses-Saunders dam at Cornwall, and a second hydro dam downstream at Beauharnois, are now the biggest sources of damage to the river and the living things in it.

The Moses-Saunders dam has so changed the flow of water upstream that whole communities of water plants, bottom-dwelling creatures and fish have been destroyed, the study says.

And it says the dam, which has raised water for the St. Lawrence Seaway since 1958, appears to make cancer-causing pollutants collect in one area just above the dam.

Half the bottom-feeding fish there have cancerous tumours around their mouths, where they rub against chemicals in the river sediment.

The huge, $2.2-million study by 35 professors and 50 students put together the first picture of the biology, water quality and human communities along the upper St. Lawrence between Montreal and Lake Ontario.

"There are a lot of consequences to these projects (big hydro dams) that are often under-appreciated," said Tom Adams of Energy Probe, a Toronto group that studies the environmental and economic effects of utilities.

The dam is owned jointly by Ontario Hydro and the New York Power Authority. Now it needs a new licence to keep operating. Hydro dams in the U.S. need a licence from the Federal Energy Regulatory Commission (FERC), and the Moses-Saunders licence expires in 2003. To renew it, its operators must prove the dam is not a serious environmental hazard.

Hydro dams, running on falling water, once were touted as clean power. But the University of Ottawa study throws new doubts on that, even though it also shows the St. Lawrence is much cleaner than local people realize.

The river carries a huge amount of water — 7,500 cubic metres, or 750 tanker truckloads, every second as it passes Cornwall. That’s more than six Ottawa Rivers in a single package.

Most of this is the distinctively blue-green water of the Great Lakes, descending on a journey that takes hundreds of years from Lake Superior.

While 70 per cent of the people of Cornwall fear the river threatens their health, the U of O study says the river water itself is reasonably clean. It has improved in the past 25 years because factories stopped pumping millions of gallons of chemical waste into it.

The toxic muck that remains, largely from old industrial processes like spreading mercury to kill slime on underwater equipment, is in localized hot spots. Downstream from Cornwall is one such location.

Public warnings against eating too much fish "are still needed because of toxic substances residing mostly in the sediment," the study says. "But sediment quality is improving as well."

The dams "stand accused of being the principal stressors (sources of stress) on the river," the study concludes.

The scientists and their students caught close to 75,000 fish over three years of netting. They measured and released most of them and saved a few for lab analysis.

They keyed in on three main species: white sucker, a bottom feeding species; yellow perch, which feed in the mid-level of the river; and northern pike, a predator at the top of the food chain.

All three species showed up in much larger numbers below the Moses-Saunders Dam than above it, they found. And the fish upstream in Lake St. Lawrence (a shallow lake created by the dam) were fewer and less healthy.

For example, half the white suckers in Lake St. Lawrence had cancerous lip tumours. Downstream from the dam, fewer than two per cent had tumours. The suckers in the area with tumour problems also had levels of polyaromatic hydrocarbons (PAHs, an industrial pollutant) that were 45 per cent higher than in suckers downstream. Their bodies were higher in mercury as well.

Upstream, the team caught only 14 pike; downstream it caught 90.

Perch were also much scarcer above the dam in Lake St. Lawrence, and they tended to be small for their age. Again, the scientists say, the dam is at fault.

The lake’s biggest problem is that it’s not really a lake, but an artificial reservoir. Lake levels don’t rise and fall along with natural, seasonal changes in the flow of water through the river. Instead, they rise and fall by about 1.5 metres a year, according to how people want the dam to operate.

"The wide variability of water levels is the big problem," says Philippe Crabbe, the head of the study team.

In winter, the unnaturally low lake levels let water freeze right to the bottom in some areas. And as ice moves downstream it "scours" the sediment, ripping out the aquatic plants that provide habitat and food for fish, crustaceans and other water creatures.

It’s a bad place to spawn and an unlikely spot for fish that do hatch to reach maturity, the study finds. "The poor habitat is certainly associated with the creation of the reservoir and dam operations, i.e. water fluctuations."

Mr. Crabbe adds, "The biodiversity never had a chance to pick up there."

Ontario’s Environment Ministry also blames the dams for trouble. "We found in our studies (for a potential cleanup) that the dam is the main disruption to habitat both upstream and downstream," said Bob Helliar of the ministry’s Kingston office.

"When they made the Seaway and flooded that land, it tends to liberate metals from the soil and you get mercury (contamination)," he said. Similar problems occurred during flooding at Hydro-Quebec’s James Bay dams, scientists have found.

Still, the water is cleaner than local people believe. This is especially true of the water flowing in from the Great Lakes; it’s the isolated hot spots from local polluted dumping grounds that tend to have the problems.

But 70 per cent of the local people surveyed in the study still believed the river was a threat to their health.

"There’s this perception problem," Mr. Crabbe said. "They have this impression that the quality of the water is much worse than it is.

"We knew (going into the study) that the St. Lawrence wasn’t as bad as European rivers, but we were surprised to see definite signs that it is improving."

Asked whether he would eat fish from above the dam, he said: "I don’t think I would. If we believe firmly that the level of contaminants is higher there, why would I want to eat that?

"I would eat fish from downstream, maybe, from Lake St. Francis. Upstream there aren’t that many fish anyway."

Shoreline wetlands are facing a major threat as well, the study says.

Mammals can survive fairly well as humans move into the shoreline areas, cutting trees and building roads, it said. But everything else — shore birds, reptiles and amphibians — have suffered a decline.

A paved road two full kilometres from a wetland is close enough to interfere with the habitat, the study found. What follows is a loss of the "richness" of wild species — fewer species in smaller numbers than before.

This is significant because most of the government wetland policies protect only a narrow strip of land near wetlands. These narrow strips, the scientists say, "are unlikely to provide adequate protection for wetland biodiversity."

Meanwhile the study admits its authors never got a chance to look at one issue that is preoccupying researchers around the Great Lakes: Water pollution that comes from the air.

Most of the old-fashioned dumping has been vastly reduced around the lakes.

Today, pesticides and other chemicals — including banned pesticides like DDT and toxaphene — continue to fall in rain after evaporating from farms in Mexico, the Caribbean or the southern United States.

Last month the head of the U.S. Environmental Protection Agency’s Great Lakes office said these airborne pollutants are now the biggest danger to the lakes.

"This issue is an important priority for future investigations," the study concludes.