The City of Calgary Waterworks owns and operates two large conventional water treatment plants, each of nominal capacity of about 450 ML/d (~120 mgd). Presently, the City of Calgary is upgrading both plants to improve water quality, water quantity, and environmental / safety performance. The conceptualization of this Upgrade Program ran from late 2000 until 2003, and then the Program moved into pre-design, detailed design, and construction activity. This paper describes the Owner / Consultant collaboration that was employed in the conceptualization of the City's Plant Upgrade Program Roadmap. Although the collaboration described is not entirely unique in its approach, it is shown to be necessary due to the complexity of the large facilities and to the complexity of the program. Also, the collaborative approach was an efficient and effective means of engaging the City of Calgary's unique Process Optimization Team, the makeup and functions of which are described in this paper. The paper discusses the benefits of this approach, and mentions a few potential issues that require consideration. Several examples of the collaborative work are given, and recommendations are made for good relationships between Owners and Consultants in collaborative Upgrade Program Roadmap development. Includes tables, figures.