This is a longitudinal case study that explored the relationship between use of organizational memory, knowledge, knowledge management, and knowledge worker productivity within the engineering group at a nuclear power plant. Three data points were taken over five years. The group used a Knowledge Management System (KMS) and it was found that the system improved effectiveness/productivity of the organization. The organization had not identified measures for determining productivity improvements so the key results of the case study are models showing the impact of knowledge use on productivity.