Mayor Jim Watson says the City will consider taking Rideau Transit Group to court, if it doesn't cover the growing cost of LRT delays.

A memo sent to council Wednesday morning said it will cost RTG as much as $8 to $10M a month for ongoing construction costs, which it must cover.

But the City is also racking up LRT-related expenses, including detours that cost about $2M monthly.

The memo said there are additional City costs that are unknown, as they won't be added up until the end of construction.

"We owe them a lot more money than they owe us, so it's in their best interest to settle amicably and to make sure the taxpayers are kept whole," said Mayor Jim Watson, speaking after council on Wednesday.

Watson says the City could withhold payments to RTG or go to court, if the builder doesn't want to pay the bill.

"They're our partners for 30 years and I don't think they want to be in court for 30 years," said Watson.

Councillor Tobi Nussbaum isn't convinced, and said it's important to remember this will be a negotiation, rather than a done deal.

"I hope the City is totally successful but I think it's important to be clear, there's no guarantee that RTG will pay for these costs," he said.

The City will be getting monthly LRT updates from now on.

The first update will be delivered at the City's finance and economic development committee March 6.