The Liberal opposition is criticizing the province's new energy plan for not mentioning replacing the province's biggest hydro dam.

The energy plan forecasts predicts NB Power's debt will drop to $4.1 billion a decade from now.

That's around when the Mactaquac dam has to be rebuilt, replaced, or decommissioned.

The cost is estimated somewhere between $2 billion and $3 billion.

The Mactaquac Dam and hydro electric generating station was built in the mid 1960s and was scheduled to operate for a century. But an ongoing chemical reaction in the concrete of the dam has led to its lifespan being shortened to 67 years, ending in 2030.

The possible refurbishment cost doesn't show up anywhere in Energy Minister Craig Leonard's NB Power debt forecasts.

"You don't see any major increases in debt or anything like that because that falls outside the ten-year range we're looking at right now," Leonard said.

Two years ago, Mactaquac seemed like an immediate issue.

The Graham Liberals said it was one reason to unload NB Power by selling it to Hydro-Quebec — the complexity of upgrading the dam was one of the reasons they gave when sale negotiations collapsed.

Liberal leader Victor Boudreau said it's too big an item for the PC government to ignore.   "To say we'll deal with that after 2020, that's just not an acceptable response to us."

Leonard said the cost of any fix or replacement for the dam will be fully reviewed before it's approved, but he said that's an "operational" issue, and his energy plan is a policy document.