Shippers say high water levels could wash away more than $1 billion in revenues

OTTAWA—Rising water levels in the St. Lawrence Seaway could cost the economy more than $1 billion, shippers and port operators say.

A new study from the Chamber of Marine Commerce warns that opening the floodgates further at a dam in Cornwall, Ont., would wash away between $1 billion and $1.75 billion in revenue for businesses on both sides of the border.

A board of control recently increased the flow at the Moses Saunders Dam—the only control point on the St. Lawrence Seaway, which includes the Great Lakes—to allow 10,400 cubic metres of water per second out of Lake Ontario. The exceptionally high rate follows heavy spring snow melt and rains and record water levels on several Great Lakes.

The rapid outflow interrupts navigation on the St. Lawrence Seaway, as swift, swirling currents near the dam slow ships’ movement through the locks.

Bruce Burrows, president of the Chamber of Marine Commerce, estimates it costs businesses up to $4 million for every day it’s in place. The International Lake Ontario-St. Lawrence River Board will consider boosting the outflow this Friday.

“Any flow over 10,400 requires some kind of stoppage—either temporary stop-and-go or full stoppage,” he told The Canadian Press.

“It’s an incremental benefit in terms of additional water being taken out of the system. It pales in comparison to the economic hit,” he stated, saying slightly higher levels could cost businesses $50 million a day in revenue.

Burrows approved of the current outflow—a heightened level that the board opted to maintain last week—due to flood problems for homeowners upstream, but called for a study into water levels and their causes along with a resiliency plan.

Lake Ontario rose to nearly 90 centimetres above average this spring, reaching a record 75.92 metres above sea level before stabilizing. Lakes Erie and Superior also hit record heights.