In the late 1980’s, Boston’s Deer Island Wastewater Treatment Plant needed an upgrade. The Massachusetts Water Resources Authority (MWRA) determined facility vulnerability to sea level rise and decided to raise key portions of the plant by 1.9 feet. The redesign and construction covered a ten year period (1989-1998) and was part of a $3.8 billion upgrade to add secondary treatment and consolidate regional treatment capacity by increasing Deer Island capacity from 250 to 350 million gallons for day. MWRA’s decision to raise portions of the plant avoided extensive costs associated with building a seawall and covered the projected vulnerability over the planned life of the facility (through 2050). MWRA considers the vulnerability of its facilities on an on-going basis using current information to assess the effectiveness of its climate adaptation actions. The Deer Island adaptation action has been re-evaluated for effectiveness within the city’s Comprehensive Adaptation Plan (Climate Ready Boston, 2013). This review used a community non-profit’s sea level rise study and concluded that MWRA’s decision to raise Deer Island is likely to be sufficient to avoid inundation of the facility over the next century.