The goal of the project was to develop a functional prototype of an environmental risk assessment parameter database on the World-Wide Web. The ability to develop a consolidated environmental database has become possible due to the phenomenal growth of the Internet and the World-Wide Web over the past few years. A large number of environmental resources do currently exist; however, with the large volume of information available, access, management, reliability, and retrievability have become increasingly difficult. To illustrate the prototype database, a practical environmental concern and the tools necessary to evaluate and characterize that concern were needed. Uranium (�������U) daughters leaching from abandoned mill tailing piles at three abandoned uranium mines in southwestern Colorado were chosen to demonstrate the database concept. The RESRAD environmental pathway modeling code served as the evaluation and characterization tool. Due to the size and complexity of RESRAD, a single radionuclide release rate equation was isolated as a controllable component of the code. The equation was a small part of the water pathway factor and examined the rate at which radionuclides absorbed in soil were leached by infiltrating water. This serves as the source term for groundwater contamination and directly applies to the �������U progeny leaching from mill tailing piles scenario. Parameters selected from the equation dealt with the background data that directly influenced the mobility of contaminates in the environment. Environmental data for the three Colorado sites were gathered and interpreted. Probability Density Functions (PDFs) were developed for input parameters and the results were then incorporated into the web site. / Graduation date: 1998