Calgary Mayor Naheed Nenshi says his Vancouver counterpart is overreacting, making questionable claims about the potential consequences of a pipeline spill in order to "end-run" regulatory processes. 

On Tuesday, Vancouver Mayor Gregor Robertson wrote an open letter to Prime Minister Justin Trudeau, calling the NEB's review of the the proposed twinning of the Kinder Morgan Trans Mountain pipeline "flawed and biased."

Mayor Nenshi, however, says Robertson's response is "really overblown."

Nenshi questioned Robertson's suggestion that an oil spill would devastate the economy. 

"He talks about hundreds of thousands of jobs being at risk, which is pretty much all the jobs in Vancouver. It really doesn't make all that much sense to me. I'd like to see where those calculations are coming from," Nenshi said.

Nenshi said the Port of Vancouver is the third largest port in North America, and that dangerous goods are transported daily in and out of those waters.

"This would take from less than one tanker a week to roughly one tanker a day. It's not a huge difference in a port that has thousands of tanker movements every single day," Nenshi said.

Faith in the regulatory process

Nenshi admitted that he doesn't have all the answers, but said neither does Mayor Robertson. 

He said he "strongly disagrees" with Robertson's view of the NEB process, and that Robertson's comments are a "disservice to the hard working civil servants who work at the regulator."

"The NEB has done its work. They put 157 conditions on this with the top technical expertise in the country," Nenshi said.

"Let's let the regulatory process work rather than end-run this with meetings between mayors and prime ministers."

With files from Colleen Underwood