California Energy Commission (CEC). Aspen supported the Western Interconnection Assessment Methodology (WIAM) project to help the CEC respond to concerns raised by the Western Governors Association (WGA) regarding the transparency and validity of resource adequacy assessments produced by the Western Electric Coordinating Council (WECC). The CEC investigated whether traditional load and resource forecasting tools were appropriate as a primary means of addressing resource adequacy issues in an environment of deep uncertainties. Broad in scope, this project supported improvements in resource adequacy assessment, methodology development and transparency in the Western Interconnection resource adequacy efforts. Aspen conducted a review of current Western Interconnection assessments. On this basis, Aspen characterized the strengths and weaknesses of existing models, tools and databases relative to performing western resource adequacy assessments. Aspen supported staff efforts by commenting on the influence diagramming products and offering citations and resources that could support further work and also aided Staff in drafting project documents and assessing the potential for using in-house modeling products in an Exploratory Modeling (EM) framework. CEC Staff and Aspen prepared a brief paper that summarized about 15 system simulation modeling tools and 7 modeling platforms. They subsequently evaluated the CEC's Supply Adequacy Model (SAM) model, which has been used by the CEC and has also been adopted by the WECC and others outside the Commission to support their respective resource modeling assessments.