To quantify potential flood-related access disruptions to medication-assisted treatment for opioid use disorder (OUD) among Delawareans. Spatial flood risk maps and infrastructure, services, and hazard risk, transportation networks, opioid treatment programs (OTPs) for the State of Delaware were integrated to visually display the relationship between these layers. A complex network theory-based simulation model was used to assess both direct (e.g., inundation with flood water) and indirect (e.g., isolation) impacts of floods. Delaware is at increasing risk from flooding associated with storms and sea-level rise, which can lead to sunny day flooding during high tides. Of the 18 OTPs in Delaware, 4 are expected to be flooded in a 100-year flood and 7 are expected to be severely disrupted, increasing to 9 by 2035 and to 10 by 2050, with service reachability less than 15 square miles due to flood-induced isolation. Individuals utilizing OTPs for OUDs must be able to access treatment programs regardless of external disruptors like floods. Because these programs require consistent treatment adherence and in-person oversight by clinicians, timely restoration of services and continuity of operations for treatment facilities in post-disaster settings is critical for treatment compliance. The State of Delaware has the third highest rate of drug overdose mortality in the U.S., with three-quarters of all drug-related deaths involving opioids. Impeded access to opioid treatment during a flood disaster can lead to relapse, overdose, and death. Hazard planning must develop policies and practices to address these risks.