The city is expected to see between 10 and 18 inches of sea-level rise by 2050, according to the Green Ribbon Commission, a coalition of local civic and business leaders partnering with the city to advance resilience and decarbonization initiatives. “Our members represent some of the largest institutions and employers in Boston, and they are telling us clearly that reducing risk from flooding is an urgent priority to be solved before it’s too late,” said Rebecca Herst, commission associate director and director of climate resilience. 

Although projects outlined in the study would require substantial investment, costs will be far higher if Boston fails to take action, city officials say. The Corps estimates the city could face $54 billion in losses by the end of the century if it does nothing. But for every $1 invested, the public sector could save at least $4 in avoided costs, according to Corps estimates. 

“The reality is that doing nothing is not a viable option. Without action, the costs to public safety and economic vitality from coastal flooding will only be compounded,” said Lt. Col. David MacPhail, deputy commander of the Corps New England District, in a statement. 

The 20 projects outlined in its feasibility study would permanently close coastal pathways that are most likely to negatively impact public safety and the city’s economy when flooded. 

The $10-billion figure cited by the Corps does not include additional cost estimates for project upgrades to improve public access to the city’s harbor. Local officials say they expect to spend billions more for green infrastructure projects along the coastline.

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Building on a 2025 report released by the state of Massachusetts, the Green Ribbon Commission analyzed funding mechanisms the city can use to pay for the 35% non-federal portion of its cost-share agreement with the federal government. 

“Our goal with this project is to really understand where we're at, to clarify the costs, the benefits, the gaps between the current investments that are being made toward resilience, and where we need to get to, and then identify a number of different strategies that we could pursue,” Herst told ENR. “The Army Corps project is a generational opportunity to receive federal funding to invest in our coastline, but Boston needs a strategy that is viable and implementable to meet the match."

Consultant Arcadis leads the commission’s coastal resilience task force, along with Throwe Environmental and the Consensus Building Institute, which has been conducting the analysis. 

“The first task is to really define the cost that we're trying to get to, and it's not just the capital cost because programs like this have to be maintained, Carly Foster, Arcadis water management practice director, told ENR. "There's going to be a broad range of potential costs that we're facing depending on the implementation schedule as well as the delivery model." 

Foster said that clients using progressive design-build for climate adaptation projects are netting one-quarter to one-third in cost savings over traditional design-bid-build approaches.

The task force plans to finalize its financial blueprint by next summer, coinciding with the Corps' final feasibility study. The agency will accept public comment on the analysis through Sept. 18.