A group opposed to Porter Airlines' proposed expansion plans for the Billy Bishop Toronto City Airport says boaters and marine shippers should be concerned.

NoJetsTO points to a report that says existing safety zones around the airport would have to be expanded if Porter is allowed to use jet aircraft.

A report by Transport Action Ontario — a public transport advocacy group — says the changes would require a major expansion of the safety zones around the airport, impacting marine activities.

The report, released Thursday, says introduction of Bombardier CS100 jets to the airport would require a runway extension of at least 168 metres at each end.

It says that unless exemptions are granted, Transport Canada's minimum requirements would result in exclusion zones that would be a severe impediment to recreational boating, Toronto Island ferry routes and lake shipping.

The report recommends that Toronto defer a decision on the airport expansion until Transport Canada has reviewed and approved the airport design.

NoJetsTO is a coalition of citizens who say they're dedicated to preserving Toronto's mixed-use waterfront and a "boutique" Island airport.

Porter has asked the city, Transport Canada and the Toronto Port Authority to amend a tripartite agreement that prevents jets from using the island airport except under special circumstances.

It has already placed a conditional order with Bombardier for 12 CS100 aircraft, with 18 options, worth about US$2.08 billion.

The greater range of the CS100 will allow the airline to fly to destinations like Los Angeles, Florida, Calgary and the Caribbean from Toronto.

If Porter's plan is approved, the first new planes are expected to be delivered in 2016.