Federal custodians of contaminated sites manage large amounts of environmental data pertaining to assessment, remediation and long-term monitoring activities. This data can spatially and temporally span many kilometers and decades. The complexity of managing large data sets increases further when users and decision-makers have a need for looking more closely at specific contaminants, time-series trends, or specific summary reports. To contextualize and make confident decisions, additional meta-data often must be incorporated into any analyses of environmental data to provide a better understanding of the site and surrounding lands. This can be effectively done through the creation, or integration, with an existing Geographic Information System (GIS). GIS enables managers, technicians and/or external contractors to quickly and effectively visualize a spatial snapshot of multiple sampling locations, sampling timelines, and analytical results without the need for time-consuming searches through hard or soft copy reports. The Environmental Sciences Group (ESG) located at the Royal Military College of Canada in Kingston, Ontario was engaged by 4th Canadian Division Support Base Environment Services, Garrison Petawawa to perform a review, adaptation and development of a GIS for scientific and environmental data management This project saw the consolidation of datasets requiring digitization from five years of paper copies, extraction from a partially completed 20-year Hydro GeoAnalyst (HGA) database, Access Databases, and Esri Geodatabases, standardization from hundreds of digital documents, followed by consolidation and conversion from several formats before migration to a GIS. By using a combination of relational database management systems (RDMS) tools, Python and/or Visual Basic for Applications (VBA) scripts, and Esri-based technologies these records were consolidated into a series of point files related to several tables ranging from several hundred records to hundreds of thousands. Currently, these data records are being connected to additional spatial datasets such as drawing sets, site photographs, survey data, aerial imagery, natural heritage features, and topographic datasets such as digital elevation models (DEM). Once, completed, it is intended that the finalised GIS will become a powerful management tool; providing insights into, for example, sighting of groundwater wells, temporal contaminant concentration trends, watershed quality, and impact of construction activities. The build methodology, and examples of effective future applications will be presented.