The city of Sausalito is raising concerns about a plan by the National Park Service to send ferries to Fort Baker, worried about more people coming to the seaside city that is already bursting at the seams on summer days with tourists on foot, buses and bicycles.

The main thrust of the park’s plan would be to establish a new, long-term embarkation site for service between the northern San Francisco waterfront and Alcatraz. But it would also establish connecting weekend ferry service to Fort Baker — near the Golden Gate Bridge — as well as between Fort Mason and other park destinations on San Francisco Bay.

As sketched out by the park service, there would be two ferries per weekend day, each boat with up to 200 passengers.

“We always look at ways to get people out of their vehicles,” said Brian Aviles, chief of planning for the Golden Gate National Recreation Area. “There is a lot to see at Fort Baker. We think this is a very modest proposal.”

Last month the San Francisco Planning Department put out a preliminary report on the Alcatraz Ferry Embarkation Project.

In response, attorneys for Sausalito filed an appeal that will be heard next month by San Francisco officials.

“The project’s proposal to provide weekend ferry service between Pier 31 1/2 and Fort Baker … will substantially increase pedestrian, bicycle and vehicular traffic along Alexander Avenue as well as in the Marin Headlands and Sausalito,” reads a letter from the city’s law firm, Sheppard, Mullin, Richter & Hampton LLP. “These additional visitors and traffic will exacerbate what are often severe, over-crowded conditions within Sausalito’s historic downtown and waterfront, particularly during weekends and peak periods spanning from March through October.”

The city is asking for an environmental impact report on the project.

Sausalito Mayor Joan Cox plans to sit down with Golden Gate National Recreation Area officials in the coming weeks to learn more about the project.

“It’s unclear what the project will exactly mean for Sausalito,” Cox said. “We want to make sure we don’t have cause for concern. We are taking these steps as a precaution. Sausalito wants a seat at the table.”

For its part the park service says the pier at Fort Baker is being looked at as a way to connect visitors to Cavallo Point Lodge, the park service’s hotel complex that sits near the foot of the Golden Gate Bridge. Opened in 2008, the property includes 142 rooms in several buildings across the Fort Baker site, and resembles a college campus more than a big-city hotel. Construction began in December 2006 and included work on the interior of the historic Fort Baker buildings, former residences, offices and meeting rooms constructed by the Army between 1901 and 1907.

Those who travel to Fort Baker via ferry could also visit the children’s Discovery Museum and take a ferry back to San Francisco, according to the park service.

The construction necessary to establish ferry service at Fort Baker would require upgrades to the existing concrete pier, which was constructed in 1937 and is used as a fishing pier presently. The work would include a new gangway, float and support piles and cost up to $2 million. Construction at Fort Baker would take about a year.