In 2013, thirty nine (39) individuals residing or working at the Wesley Ridge Retirement Community contracted Legionnaire’s Disease. This remains the largest outbreak of this disease in Ohio history. Within 4 hours of the initial call, Lawhon mobilized to the site to begin a comprehensive investigation to identify potential environmental sources of Legionella on the campus. As part of this effort, L&A reviewed mechanical plans for each of the four facilities, documented water temperatures at critical points and collected more than 100 samples for laboratory analysis. Concurrent with field sampling activities, strategies and procedures to protect residents and decontaminate the potable water system and the cooling tower were developed in collaboration with the Centers for Disease Control, Ohio Department of Health (ODH), Franklin County Board of Health and the client. L&A assisted Wesley Ridge with the identification of water treatment contractors and the procurement of bids. We answered technical questions during the remediation process and monitored Legionella concentrations at each building during and after decontamination activities. L&A continues to perform routine environmental monitoring at the site to document engineering and administrative controls are limiting the proliferation of waterborne pathogens in potable water systems. Until the system was decommissioned, we also collected water samples from the cooling tower to document Legionella and HPC counts were within acceptable limits. L&A is currently assisting Wesley Ridge in updating their existing waterborne pathogen management program for compliance with the new ANSI/ASHRAE Standard 188-2015, Legionellosis: Risk Management for Building Water Systems.