In general, the planning and operation of the Canadian Treaty projects does not recognize operations not defined in the actual Treaty or Treaty Protocol. Since the Phase 1 studies were primarily focused on looking at the two fundamental river purposes defined under the Treaty, power and flood control, the studies did not include additional operations not considered under the Treaty. By approaching the Phase 1 studies from this Treaty standpoint, both the U.S. and Canadian Entities believed they created a baseline of information for comparison and to build from for future studies and for engagement with the sovereigns and stakeholders within their respective countries. However, since the Biological Opinions (BiOp) have such a strong influence on the U.S. operations, the U.S. Entity felt it was important to look at the Phase 1 study results with the fish operations included. The purpose of this appendix is to describe the modeling, methodology and criteria used in the U.S. Entity Phase 1 Supplemental studies that were done to assess the impacts to the U.S. system and fish operations when BiOp requirements were overlaid on the Phase 1 studies. The Phase 1 studies referred to in this appendix are: 1. Treaty continues post-2024 and Called Upon flood control is implemented (Study A); 2. Treaty is terminated in 2024 and Called Upon flood control is implemented (Study B); and 3. Treaty continues post-2024 with largely the same Treaty and flood control operations as today (Study C). The purpose of this Appendix is to explore how system operations with Biological Opinion strategies performed in Called Upon years.