The costs involved with mine drainage treatment continue to increase while the necessity to treat this contaminated water continues in perpetuity. Understanding the geochemical processes that occur during the mine drainage treatment process through chemical addition, oxygen addition, settling, sludge deposition and storage, to the final system effluent requires prudent monitoring of the system components by measuring water quality before and after each process. The Geochemist Workbench® software allows the modeling of water using laboratory and field data for certain key parameters to predict the treatability of the water with the various alkalinity and aeration technologies available today, including passive treatment. This predictive modeling software is becoming an extremely important component in Skelly and Loy’s approach to designing the most appropriate treatment system technologies for each AMD discharge. The types of AMD discharges to remediate are becoming more challenging and, with the increased scrutiny of passive treatment system application, modeling results obtained from the Geochemist Workbench® meet or exceed the highest level of scrutiny. When faced with looking at considerations from a watershed restoration approach, the Geochemist Workbench® software is useful to identify the priority AMD discharges within a watershed and model the future treatment of those identified discharges and predict the improvements in the receiving stream. Skelly and Loy’s engineering and scientific experts employ the powerful Geochemist Workbench® software tool in AMD treatment system design, troubleshooting and improving existing problematic systems (passive and active), and watershed assessments for prioritizing and remediating AMD discharges as part of watershed restoration efforts.