A draft feasibility study outlining Boston coastal flood protection across 16 miles of urban shoreline has been released jointly by the city of Boston and the US Army Corps of Engineers, proposing 20 separate infrastructure projects at a combined cost of around $10 billion.
The study projects that, without intervention, flooding could cost the city as much as $54 billion by 2090, with historic buildings, neighbourhoods, and particularly transportation systems bearing the brunt of that damage. The $10 billion figure represents roughly a fifth of that projected loss, framed explicitly as the cheaper path.
‘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 US Army Corps of Engineers New England District, in a statement.
What the Boston Coastal Flood Protection Study Found
Boston is expected to see between 10 and 18 inches of sea level rise over the next 25 years. The Corps estimates that virtually the entirety of the city will experience inundation during a 100-year storm event over the next 64 years. The projects proposed in the study would span from above Powder Hill in the north to Columbine Cliffs in the south.
Planning strategies in the study focused on managing storm risks both now and in the future, modelled across several different sea level change scenarios and calibrated to each neighbourhood’s needs and capacities. The study’s own summary acknowledges these are decisions made under substantial uncertainties, with engineering costs for measures such as seawalls still highly variable. No specific designs have been finalised.
The projects are intended to be delivered in stages, matching the phased worsening of sea level rise over coming decades. The Boston.gov announcement confirms the full feasibility study is projected to be completed by 2028, giving the city and federal partners several years to refine costs and designs before major construction commitments are locked in.
Federal Funding and the Question of Boston’s Match
One of the most concrete details to emerge from the plan concerns how the projects might be financed. According to Boston.gov, the city can access up to 65% federal cost-sharing to construct coastal resilience projects of this kind, meaning Boston would need to fund the remaining share from local and state sources. That local contribution, on a $10 billion programme, is not a small number, and it is the part of the equation the city still needs to solve.
Rebecca Herst, Green Ribbon Commission associate director and director of climate resilience, was direct about what comes next. ‘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,’ she told Engineering News-Record. The Green Ribbon Commission’s coastal resilience task force plans to finalise its financial blueprint by next summer, timed to coincide with the Corps’ final feasibility study.
Consultations on engineering effectiveness, economic opportunities, and environmental impacts have already taken place, drawing in both the task force and wider resource agencies and stakeholders. Federal government interest was confirmed during that process.
‘The future of our city depends on the steps we take now to build resilient communities,’ Mayor Michelle Wu said in a statement. ‘With more frequent flooding in vulnerable areas during extreme weather events, the Coastal Storm Risk Management Feasibility Study is critical to understanding how to protect inland neighbourhoods most at risk and unlocking resources to take action.’
The Corps is accepting public comment on the analysis through 18 September. The task force’s financial blueprint, due next summer alongside the final study, will determine whether the city can actually move from a feasibility document to ground-breaking on what would be one of the largest coastal infrastructure programmes in US history.
