The events of September 11, 2001, increased and intensified domestic preparedness efforts in the United States against terrorism and other threats. The heightened focus on protecting this nation’s critical infrastructure included legislation requiring implementation of extensive new security measures to better defend water supply systems against physical, chemical/ biological, and cyber attacks. In response, municipal officials have implemented numerous safeguards to reduce the vulnerability of these systems to purposeful intrusions including ongoing vulnerability assessments, extensive personnel training, and highly detailed emergency response and communication plans. This study evaluates fiscal year 2010 annual compliance assessments of public water systems with security measures that were implemented by Mississippi’s Department of Health as a response to federal requirements to address these potential terrorist threats to water distribution systems. The results show that 20 percent of the water systems in this state had at least one security violation on their 2010 Capacity Development Assessment, and continued perseverance from local governments is needed to enhance the resiliency and robustness of these systems against physical threats.