EVAMIX is a sophisticated decision support tool that has been applied in a variety of water resource planning applications. A key to developing a well structured, consistent approach to Source Water Assessment is the technique chosen to screen and prioritize the hundreds, or in large systems, thousands of potential point and nonpoint sources within the watershed. The evaluation/prioritization approach developed for the Philadelphia Water Department (PWD) illustrates the application of EVAMIX to PWD's Queen Lane Intake on the Schuylkill River. Matrix based methods of evaluation have been available since the early 1960s. Their development was specifically targeted for planners and engineers to evaluate alternative plans, sites, or technologies with the objective of selecting the best one, or ranking the alternatives for presentation to decision makers. EVAMIX, developed during the 1980s in The Netherlands, was designed to make use of the best aspects of both concordance/discordance analysis and the Goals Achievement Matrix to handle both quantitative and qualitative data in a mathematically rigorous fashion. It is a matrix based, multi-criteria evaluation program that makes use of both quantitative and qualitative criteria within the same evaluation, regardless of the units of measure. The algorithm behind EVAMIX maintains the essential characteristics of quantitative and qualitative criteria, yet is designed to eventually combine the results in a single appraisal score. This unique feature gives the program much greater flexibility than most other matrix based evaluation programs, and allows the evaluation team to make use of all data available to them in its original form. The SWAP for PWD's Queen Lane Intake on the Schuylkill River is an excellent example of the successful application of this decision support tool. As a result of the study, PWD was provided with a list of the top 100 potential pollutant sources from the thousands of potential sources identified during the project. These are currently being addressed in PWD's Source Water Protection Program. Includes 10 references, tables, figures.
