This powerpoint presentation begins by providing a brief overview of the Massachusetts Department of Environmental Protection (MassDEP) Western Region, and a PWS Regional Profile. Part 1 of the presentation presents External Training - Public Water Systems, Winter/Spring 2007 that includes the following training modules: Module 1 - the Development of an Effective Emergency Response Plan; Module 2 - Tabletop Exercise, Disruption Due To Weather Event; Module 3 - NIMS and ICS Training; and, Module 4 - Tabletop Exercise, Potential Contamination of a Water Supply. Part 2 of the presentation presents Inspections PWS Caustics Initiative and had the following objectives: identify the components, operational characteristics, and safety features where caustics are used; and, identify PWS vulnerabilities to caustic chemical overfeed. Part 3 of the presentation presents Emergency Response Assistance Case Studies.