CITY HALL -- It’s no secret that some Islanders, especially on the South Shore, are upset about the city’s new fast ferry route being added to an area with existing ferry service.

But Mayor Bill de Blasio said Monday at a press conference in Coney Island announcing the newest NYC Ferry routes and expansions that the door is still “open” to thinking about other fast ferry stops in the future.

Come 2021, de Blasio said he plans to do another assessment to see if more fast ferry routes are needed around the city.

“We would love to keep seeing additional routes added but they have to be viable in every sense,” he said. “These were ones we had a high level of confidence in but given the success that NYC Ferry has experienced so far and given the possibility of cross registering the ferry with the [Metropolitan Transportation Authority], we’re going to keep an open door to further expansion in the future and I think the logical time to do that is after these lines are in place, so that will be by the summer of 2021.”

The new route will run from St. George to Battery Park/Vesey Street in a total of 18 minutes.

It will continue on for another 17 minutes from Battery Park City/Vesey Street to Midtown West at Pier 79/West 39th Street.

The trip will run for a total of about 35 minutes.

BARGE TO BE BUILT AT SLIP 7

NYCEDC President and CEO James Patchett said the city plans to build a barge at an existing ferry slip -- Slip 7 -- which is off to the right side of the St. George Ferry Terminal if you are looking toward Manhattan.

Patchett said NYCEDC has been working closely with the Department of Transportation and the U.S. Coast Guard to ensure the new route will not impact existing Staten Island Ferry service.

The St. George route is expected to serve between 1.5 million to 2 million riders annually.

The new St. George route will run every 24 minutes during peak hours and it will cost the city $44 million in capital costs, according to the latest projections outlined in a feasibility study on fast ferry expansion released by city’s Economic Development Corporation Monday.

The report showed the city initially looked at seven potential sites: St. George, Stapleton, Great Kills Park, Tottenville, New Dorp Beach/Midland Beach, Prince’s Bay, and the West Shore.

That list was then narrowed down to five route combinations NYCEDC closely studied:

St. George > Battery Park City > Midtown / West 39th Street

Stapleton > Battery Park City > Midtown / West 39th Street

St. George > Battery Park City > Midtown / West 39th Street > West 70th Street

St. George > Battery Park City > Chelsea (Pier 57) > Midtown / West 39th Street

Great Kills > Battery Park City > Midtown / West 39th Street

But the city decided on the St. George route, concluding it would “serve the most people for the lowest operating costs of Staten Island.”

The report notes the existing St. George Ferry terminal already provides transit connections from all areas of the Island which could provide “travel time savings” for those going to lower and Midtown Manhattan.

MAYOR SAYS OTHER ISLAND SITES WERE ‘PHYSICALLY VERY VERY DIFFICULT’

“We looked long and hard at the options you may know that I went with [Borough President James Oddo] and other elected officials to look at sites on the South Shore,” the mayor said. “I certainly felt that there was some understanding after that tour that those sites were physically very very difficult and, unfortunately, weren’t viable. We also have to think about sites in terms of what kind of ridership we knew they would get cause this is an expensive endeavor to put together. Once it has a strong ridership, it’s worth it, but it’s a lot to build it up and we didn’t see a place that worked properly.”

De Blasio also emphasized that getting to the West Side of Manhattan was something a lot of Staten Islanders wanted and would allow Island commuters to get to job sites at places like the Hudson Yards development.

Following news of the addition of St. George to NYC Ferry, Oddo said he planned to set up a call with MTA President Andy Byford to see if the agency would go for running express trains from the South Shore to St. George so that commuters on the South Shore can use the new fast ferry route too.

He also said he would continue to work with Arthur Imperatore, the president and founder of NY Waterway, to potentially bring a private fast ferry to another part of the Island, be it the east side of the North Shore, Mid-Island, or the South Shore.

Other Island elected officials like South Shore Councilman Joe Borelli (R) and Minority Leader Steven Matteo (R-Mid Island) also said they would continue to push for additional ferry routes on the South Shore and Mid-Island.

The city plans to launch the new route sometime in 2020. It will cost commuters $2.75 per ride and the city plans to provide a subsidy of $7-$8 per rider.

FOLLOW SYDNEY KASHIWAGI ON TWITTER.