Models used in risk assessment for chemical spills should realistically represent real-world spills. The U.S. law titled Clean Air Act Amendments (CAAA) of 1990 mandated risk management. The risk management program may be defined by internal facility documents and encompasses all aspects of the design, operation, and maintenance of a facility handling a regulated substance such as the chemical chlorine. The risk management plan is in addition to reporting requirements under the Emergency Planning and Community Right-to-Know Act of 1986, also known as Title III of the Superfund Amendments and Reauthorization Act. The CAAA requirement makes a distinction between a risk management program, which is internal to the facility, and a risk management plan, which must be submitted to federal, state, and local entities. Chlorine uses and accidents are reviewed. Environmental concerns have also resulted in legislation phasing out many classes of chlorine-based herbicides and pesticides as well as some chlorinated organic solvents. Example chlorine spills are given to illustrate problems in using models for risk assessment. The source term (how the chlorine escapes into the air) may be poorly or inaccurately characterized in most models and may not represent reality. Testing of mitigation technology at places such as the Nevada Spill Test Facility is necessary to develop effective emergency response. To overcome some of these inadequacies, Western Research Institute and Desert Research Institute have planned a series of chlorine evaporation rate measurements to be performed at the Nevada Spill Test Facility in 1994.