BOSTON MAYOR MARTY WALSH wants to transform Fort Point Channel into a waterway lined with parks that would serve almost as levees during periods of storm surge.

During an address to the Greater Boston Chamber of Commerce, Walsh said he envisioned using fill to build slightly elevated parks up and down the length of the Fort Point Channel that would essentially serve as sea walls.  The channel itself would be broken up with man-made islands, salt marshes, and gently sloping pathways down to the water.

The goal is to divert water coming into Boston Harbor during a storm surge down Fort Point Channel,  where it could dissipate without flooding parts of the city. The project would give downtown, Chinatown, and South Boston access to parks – “a new jewel in our park system,” Walsh said – and provide protection during storms.

“It’s a big expense and it’s a big idea and it will take awhile,” Walsh said, adding that the money for the work will be a combination of public and private funds. The mayor offered no timetable for the project.

Walsh said the city has been working on the idea with the Trustees of Reservations, which received $1.7 million in funding for planning from the Barr Foundation and other donors. Nick Black, the managing director of the so-called Boston Waterfront Initiative at the Trustees of Reservations, said Fort Point Channel currently is a long, straight body of water hemmed in by cement walls.

Black said he envisioned parks being built up along the channel’s edge, raising the height by three to five feet, with gently sloping passages down to the water in a number of locations. He said islands and other structures out in the channel could also be constructed.

“Instead of being a flume of water rushing straight down to Dorchester, these elements would break the water up and slow it down,” Black said.

More trains on the Fairmount Line

Walsh called for increased train service on the little-used Fairmount commuter rail line, which runs from Readville through Roxbury and Mattapan into South Station.

The mayor was vague about what type of service he wanted, but his appeal seemed to echo legislation being pursued on Beacon Hill that would require the T to launch a pilot program offering more frequent trains on the Fairmount Line and the ability to use Charlie Cards to make transfers to subways and buses. Trains currently run about once per hour during peak periods; the legislation calls for trains every 15 minutes peak and every 30 minutes off-peak.

Walsh said one-fifth of Boston’s population lives along the Fairmount Line’s route. He said 83 percent of those residents are black or Latino. “They deserve better service,” he said.

Walsh, a former union leader, suggested the T needs to put aside its preoccupation with privatizing operations. He also said the T needs to pay more attention to Boston’s concerns.

“The MBTA needs to work with us. We’re the largest single payer into the MBTA,” he said, noting the city’s $85 million-a-year contribution. “We need a bigger voice at the table working with the T.”

Walsh also gave a shoutout for greater use of public transit. “In Boston, we have a mindset of taking cars everywhere. Even though the MBTA at certain times has problems, most days it’s reliable, most days it’s on time,” he said. “So we need to get people thinking outside the box and thinking public transportation more.”

Boston’s bid for Amazon

Walsh said a tax incentive package will probably not be included in Boston’s initial bid for Amazon’s second headquarters.

The mayor said the city has the housing, the workforce, and the business climate to land Amazon, and that’s what Boston will focus on in its submission. “I’m not viewing it as a tax incentive package,” he said. “I’m viewing it as how do we get this company to our city.”

Walsh said he assumed Amazon will narrow the field to a small group of cities, who will then be asked to develop proposals that go into greater detail. A tax incentive package might be offered at that point, he indicated.

The mayor said he wasn’t releasing details of the city’s offer because doing so would give competitors an advantage. “We’re competing with other places. If I read it all over the front page of the paper, other cities will see that,” he said.

“Let’s not make this a story of me not telling stuff,” he said when reporters asked why he was being so secretive. “We’re trying to attract a company bringing 50,000 jobs and $5 billion in investment. It’s a good thing.”

Chamber endorsement

James Rooney, the president of the Greater Boston Chamber of Commerce, made clear where he stands in the next mayor’s race in his closing remarks. “The Chamber of Commerce does not endorse candidates for elective office,” Rooney said to Walsh. “But thank you for doing such a great job and thank you for your partnership with the business community and we look forward to seeing you here again next year.”

The election for mayor is in November.