Mactaquac Dam upgrade gets environmental go-ahead

New Brunswick's largest hydroelectric dam is one step closer to a multibillion-dollar refurbishment to extend its lifespan.

The province has given N.B. Power the green light to proceed with a major fix of the Mactaquac Dam following a two-year environmental impact assessment.

But there's still no definitive decision to go ahead, as policymakers grapple with the enormous financial impact of the project on ratepayers.

The latest estimate of the cost is $7.5 billion to $9 billion.

Mactaquac went online in 1968 and was supposed to operate for 100 years. It now generates about one-fifth of all the province's electricity, with no greenhouse gas emissions that contribute to a warming climate.

But a chemical reaction in the concrete aggregate has caused it to expand.

"This reaction has resulted in substantial cracking, leading to accelerated concrete deterioration and seepage of headpond waters through the structures," N.B. Power wrote in its EIA submission in 2023.

The reaction "affects the performance of the powerhouse, water retaining structures, gates, and generating units."

That means a major overhaul is needed soon.

WATCH | Major hydro dam project gets OK — with conditions: 

Mactaquac Dam overhaul wins environmental approval

1 day ago

Duration 1:23

Province gives green light to multibillion-dollar refurbishment of New Brunswick’s biggest hydro dam.

The utility pointed to the growing demand for non-emitting electricity to justify the project.

The province says N.B. Power can proceed as long as it meets certain conditions, including implementing temporary fish passageways and a plan for wells and wastewater.

The utility must also consult First Nations communities and must agree to stop work and consult the province "if it is suspected that remains of archaeological significance are discovered" during the project.

And it must comply with federal fisheries legislation and needs to apply for provincial permits for any work that would affect a watercourse or wetland.

Neither the province nor N.B. Power had an immediate comment on the EIA decision, but Energy Minister Rene Legacy said in April that the Energy and Utilities Board would review the cost of the project to allow the government to make "an informed decision."

N.B. Power is already carrying a debt of more than $5 billion, most of which has been attributed by an auditor-general's report to the Point Lepreau and Belledune power plant projects and the more recent Point Lepreau refurbishment.