This research project aims to identify, list, and characterize chemical occurrence databases and data sets that can be used by states and utilities to perform source water assessments. The data sets were inventoried and reviewed based on a variety of descriptors (metadata). Amendments to the Safe Drinking Water Act (SDWA) require all US states to establish Source Water Assessment Programs (SWAPs). This includes the submission of a plan to the USEPA detailing how the states will delineate source water assessment areas, inventory significant contaminants in these areas, and determine the susceptibility of each public water supply to contamination. The collection of existing data on chemical occurrence is one tool to help determine potential contaminants and perform susceptibility analyses for surface and groundwater. This project includes a review of available, relevant source water data sets (e.g., surface water and groundwater) that document chemical occurrence in an effort to develop a comprehensive data inventory to serve as a central resource when performing SWAPs. Data sources queried to accomplish this task included national databases and data sets available through regional and state agencies, water utilities, and volunteer groups. The majority of databases and data sets included in this research project were identified as a result of the participation and cooperation of local and state agencies. The project team also identified national data sets and some state and volunteer groups? data sets through online research. The product of this research has extensive application to the drinking water and regulatory communities for assessing source waters, enriching the ability to assemble and evaluate all existing and readily available water quality-related data and information. Specifically, this project documented chemical data stored in a variety of databases and provided a mechanism to access it and the associated metadata. The online tool, Source Water Quality Database, provides information on water quality data related to chemical occurrence stored in national, regional, and state data sets. Originally published by AwwaRF for its subscribers in 2003 This publication can be purchased and downloaded via Pay Per View on Water Intelligence Online - click on the Pay Per View icon below