Development of a BCA Cost Test Rule for Integrated Electric-Gas System Planning

Synapse provided Washington Utilities and Transportation Commission (UTC) Staff with technical support to facilitate the development of a cost test for integrated system planning (ISP) as required by ESHB 1589, the Decarbonization Act for Large Combination Utilities (Decarbonization Act). Among other items, the Decarbonization Act directed the UTC to establish by rule a cost test for emissions reduction measures achieved by large combination utilities to comply with Washington state clean energy and climate policies. The rulemaking requires each large combination utility to use the cost test as a key input in the selection of its ISP preferred portfolio and as an input to UTC’s determination on whether the ISP is in the public interest. To support the development of the cost test rule, Synapse collaborated with staff, assisted with the writing of draft rules, and attended several workshops to get input from a variety of stakeholders. The amended ISP rules were adopted by the UTC in September 2025.