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Chapter IV
Database Modification

Once the PWS coordinate values were collected, post-processed, and transferred to a table, it became necessary to modify the source and system tables to accommodate additional fields. The source table was significantly altered to fall in compliance with standards established by the Definitions for the Minimum Set of Data Elements for Ground Water Quality (USEPA, 1992b). Although USEPA's Safe Drinking Water Program Database followed these standards, this project included the use of only the system and source tables which together would serve as a "stand alone" Wyoming PWS geographic information system database.

The majority of the supplemental elements aided in describing the methods and errors associated with data gathering techniques. Additionally, some fields were developed that specifically relate to this project. Appendices B & D detail the structure of the two tables with Appendices C & E describing each field's significance and associated attribute options.

Added fields within the tables are denoted with an asterisk (*) in Appendices C& E. The system table has only one addition being the UW-UPDATE field. The source table has a multitude of changes. The most apparent of these changes is the additional latitude and longitude fields. The original database had a field for degrees, minutes, seconds for both latitude and longitude. For GIS conversion however, it was necessary to create a field that had each coordinate in decimal degrees. This allowed for the source table, the decimal degrees fields specifically, to be used in creating a spatial database. One other notable field is the REASON code which describes why the groundwater source was not located during this project or if it was a new source not listed in USEPA's database.

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