It can come down to a matter of centimetres.

A few too low, and commercial shipping vessels must carry less cargo, losing their competitive advantage over road and rail — and the recreational boating season is cut short. A few too high, and homes are damaged and wetland plants killed.

So adjusting the regulations governing how the water levels of Lake Ontario and the St. Lawrence River are managed is a tricky business to navigate — and one that has been done very slowly.

If you’d told John Hall, the co-ordinator of the Hamilton Harbour Remedial Action Plan, 14 years ago that he’d still be waiting for the change, he’d have scoffed.

But a $20 million, five-year study and $360,000 in public and technical hearings later, he is hopeful that the tide has finally turned.

After a 2008 plan was resoundingly rejected by stakeholders, a new plan is poised — barring some tweaking — to be recommended by the a new plan for federal approval by both the U.S. and Canada by early next year.

The International Joint Commission, a body of six Canadian and U.S. members, was created to handle issues in shared waters like the Great Lakes.

Conservation groups on both sides of the border, including Conservation Ontario and the Toronto and Region Conservation Authority, have given it their blessing. So has the Montreal Port Authority. Boating Ontario sees, as executive director Al Donaldson put it, “no need to panic.”

Robert Houze, who owns Iroquois Marine Services, says the new rules may allow the boating season for deep-keeled boats to go on a few weeks longer. The Canadian Shipping Association is concerned about the plan’s ability to allow quick changes when water levels are too low, says president Robert Lewis-Manning, but he’s optimistic that can be addressed.

But still beating ceaselessly against the current are property owners on the south shore of Lake Ontario — where the water is lapping almost at their front doors.

“We are disproportionately affected,” says Dan Barletta, a member of the Lake Ontario Riparian Alliance. It is their homes, their sewer systems and their flood insurance premiums that will suffer most under the new plan, he says.

Barletta has lived in Greece, N.Y., since 1985, in a lakeshore neighbourhood that has existed since 1887.

“The lake has come to us,” he says of the thousands of homes he says will be affected by the new plan. “We didn’t go to the lake.”

Lake Ontario levels are adjusted by controlling the amount of water released by the Moses-Saunders dam at Cornwall, Ont., and Massena, N.Y. The current system, in place since 1958, aims, despite the best efforts of Mother Nature, to keep lake levels within a 1.2-metre range, depending on time of year.

The new system intends to mimic the natural seasonal water levels of Lake Ontario, which means there will be both higher and lower water levels than now.

That means that homes on the Lake Ontario shoreline will face an increase in erosion and risk of flooding from the current plan — $2.22 million annually. Overall, there is a $3.12 million economic benefit to the new plan over the current one, due to $5.26 million in increased hydropower generation.

Barletta says most of that damage will be on the south lakeshore, and that the potential damage has been drastically undervalued.

“This plan is awful,” Barletta said at a recent public hearing organized by the commission. “It is beyond imagination that you are considering it.”

At the week of public hearings held in July, battle lines were drawn between property owners and the environmental groups.

Loading... Loading... Loading... Loading... Loading... Loading...

It became, as the IJC commissioners observed in a technical hearing in Toronto, a matter of muskrats versus homes.

The new plan, with the periods of high and low water, does indeed benefit muskrats — a species used as an indicator of the healthiness of wetlands — as well as “vegetation, fish and other critters,” says Dick Hibma, the chair of Conservation Ontario. Without that variation in depth, you end up with marshes full of nothing but cattails.

John Hall, who sat on a public advisory committee during the five-year study, said he “wanted the south shore people to understand that those public agencies and private property owners that own wetlands are also property owners and have a major public investment in wetlands that have an economic value … A big reason people visit and spend tourism dollars is because of the natural lands like Cootes Paradise marsh, in the Royal Botanical Gardens.”

It’s easy to look to the south shore from Toronto “and say public safety should be first,” says Nancy Gaffney, a waterfront specialist with the Toronto and Region Conservation Authority.

The new plan hardly affects homes in Toronto and much of the Ontario side because shoreline development regulations put in place by the province after the devastation of Hurricane Hazel in the 1950s mean that homes are mostly well out of the hazard zones, she says.

“The coastal wetlands are our focus, and the south shore isn’t even close to that. But this issue isn’t about people versus muskrats at all, it’s about public safety ... I would hope these people have a sober second thought. If the waves are brushing against your window, it’s not the best place for your family to be, regardless of your rights.”

She hopes the plan’s much-touted “adaptive management strategy” will help find ways to provide people in vulnerable shoreline areas the assistance they need, whether it be moving houses entirely or providing some kind of protection.

The strategy boils down to monitoring the effects of changing water levels — something that could help the commission react more quickly to changing conditions caused by climate change, says Hall.

But as commission co-chair Lana Pollack notes, “monitoring isn’t sexy.”

And since no specific pilot programs have been listed and no provisions for funding have been made in the plan, there is concern that it will be a challenge to persuade various levels of government to sign off on it.

The commission is accepting public comments on the plan until the end of August. If stakeholders, including Ontario, Quebec and New York State, support the plan, it could go up for federal consideration next year.

Bluffer’s Park marina owner Ross Merikallio isn’t holding his breath, though. When it comes to water management issues, from Lake Ontario to the dangerously shallow Georgian Bay , he says waiting for change is “like waiting for the Scarborough subway.”

Read more about: