Since the September 11, 2001 terrorist attack on the United States there has been a renewed interest by various organizations to evaluate appropriate security measures to prepare for the threat of additional acts of terrorism. Acts of terrorism directed at drinking water utilities have been reported previously. In response to these attacks the water industry has been directed to develop vulnerability assessment plans. In general, these plans focus on evaluating points of system vulnerability to terrorist attack via destruction of facilities or by introduction of contaminants into the system. While many water agencies have existing emergency response plans to address catastrophic events (e.g., floods, earthquakes, tornadoes, etc.) they typically do not focus on terrorist events involving intentional contamination with chemical, biological or radiological agents. Consequently, many utilities require external assistance from organizations with experience in developing security plans. Generally, these agencies have expertise in measures to protect against destruction of facilities but frequently lack expertise to evaluate chemical, biological, or radiological agents that might be used to contaminate drinking water systems. Indeed, this type of expertise is typically limited to the military or select government organizations. However, current events have necessitated dissemination of this information, but due to the classified nature of this issue it is extremely difficult for water agencies to acquire information on contaminants of concern. Furthermore, detection methods for several of these contaminants are extremely complex or may not be readily available to most laboratories. Consequently, development of effective monitoring and analytical strategies to complement vulnerability assessment plans is challenging. However, water utilities with laboratory facilities can implement intervention strategies but must address a number of critical issues. Includes 2 references.