During a Legionnaires' disease outbreak at a Missouri hotel in 2015, the Centers for Disease Control and Prevention assisted state and local health departments to identify possible sources and transmission factors and to recommend improvements to water management. We performed an environmental assessment to understand the hotel’s water systems and identify areas of risk for amplification and transmission. We obtained samples from the pool, spa, and potable water systems for Legionella culture. In the potable water system, we noted temperatures ideal for Legionella amplification and areas of water stagnation. Additionally, we found inadequate documentation of pool and spa disinfection and maintenance. Of 40 water samples, Legionella pneumophila serogroup 1 that matched the sequence type of one available clinical isolate was recovered from five sink and shower fixtures. A comprehensive environmental assessment proved crucial to identifying maintenance issues in the hotel’s water systems and underscored the need for a water management program to reduce Legionnaires' disease risk.