RPCG – 2026 CCTA Results and Next Steps Colby Johnson & Vijay Satyal Western Electricity Coordinating Council

Western Electricity Coordinating Council RPCG process Every 2 year effort Prior webinars- June, October Focus of this webinar- Discuss voting results to WECC proposed “include” and “exclude” list Future meeting/webinar to discuss adjustments Western Electricity Coordinating Council

Colby Johnson, Associate Engineer 2026 CCTA Results Colby Johnson, Associate Engineer Western Electricity Coordinating Council

Western Electricity Coordinating Council Overview CCTA Selection Process Review CCTA Criteria Flow Chart Transmission Projects: Under Construction Met Criteria 1 &2: Default Inclusion Ballot Review: Inclusion/Exclusion List Transmission Projects: Not Under Construction Did meet Criteria 3 & 4 & 5 (if necessary) -> Inclusion Did not meet Criteria 3, 4, 5 -> Exclusion Polling Tie Projects: Include/Exclude? Final 2026 CCTA Project List Future Improvements Western Electricity Coordinating Council

CCTA Selection Process Review 2026 CCTA Inclusions All Prior CCTA Projects 2026 CCTA Criteria Under Constr. Not Under Constr. Newly-Submitted CCTA Projects 2026 CCTA Exclusions Western Electricity Coordinating Council

CCTA Not CCTA Criteria 1 No Yes Criteria 2 Criteria 3 Yes No No Yes Regional Significance No Project A Project … Project Z Yes Criteria 2 Under Construction Criteria 3 Financial Indicators Yes No No Yes Criteria 4 Implement. Indicators Yes No Passed RPCG Screen Criteria 5 Dependency Check N/A No CCTA Yes Not CCTA Western Electricity Coordinating Council

Transmission Projects: Under Construction These Projects Met Criteria 1 & 2; Included in CCTA Central Ferry – Lower Monumental - Complete and In-Service Delaney-Palo Verde 500kV Line Delaney-Sun Valley 500kV Line Desert Basin - Pinal Central - Complete and In-Service Devers - Colorado River 500 kV (DCR) Transmission Line Project - Complete and In-Service Energy Gateway Transmission Project - Segment G (Sigurd - Red Butte 345 kV line) - Complete and In-Service Hassayampa - North Gila 500kV #2 line - Complete and In-Service Interior to Lower Mainland Transmission (ILM) Project Pinal Central-Tortolita - Complete and In-Service Pinal West-Pinal Central-Browning (SEV) - Complete and In-Service West of McNary Reinforcement Project Group 2 (Big Eddy - Knight) Western Electricity Coordinating Council

Ballot Results Neutral votes not counted In instance of a “tie”, this group to determine Western Electricity Coordinating Council

Western Electricity Coordinating Council Transmission Projects: Not Under Construction Poll Majority – Agree to Include Met CCTA selection Criterion 3, 4, and/or 5 (when applicable): Boardman-Hemingway 500 kV (B2H) Delaney - Colorado River 500 kV Transmission Project (Ten West Link) Energy Gateway: Wallula – McNary (230 kV) Energy Gateway South: Aeolus-Mona (500 kV) Energy Gateway West: Bridger – Populus Energy Gateway West: Windstar to Jim Bridger Energy Gateway West: Midpoint – Hemingway Energy Gateway West: Populus – Midpoint Energy Gateway West: Populus – Cedar Hill - Hemingway Centennial II: Harry Allen - Eldorado 500 kV Transmission Project I-5 Corridor Reinforcement Project (Castle Rock - Troutdale) Morgan-Sun Valley 500kV Line *Path 8 Upgrade/Colstrip Transmission Upgrade *Pawnee-Daniels Park *Updates provided after poll sent out; 2 additional “Inclusions” Based on updates, two “new” projects to inclusion list. Are there any disagreements? Western Electricity Coordinating Council

Did not meet Criteria 3, 4, and/or 5: Transmission Projects: Not Under Construction Poll Majority – Agree to “Exclude” Did not meet Criteria 3, 4, and/or 5: Bighorn-Eldorado Centennial West Clean Line Chinook Centennial II (Amargosa-Northwest) Centennial II (Northwest - Harry Allen) Great Basin HVDC Harcuvar Transmission Project Hemingway-Captain Jack 500 kV Transmission Line Juan de Fuca HVDC Sea Cable Juan de Fuca II HVDC Cable Lamar-Vilas Lassen 230kV East/West Tie Lucky Corridor Transmission Project Mountain States Transmission Intertie (MSTI) (Townsend-Midpoint 500 kV) North Gila - Imperial Valley #2 Project NV Energy Robinson - Harry Allen 500 kV Line Southern Nevada Intertie Project (SNIP) Southwest Intertie Project - North (SWIP-North) SunZia Southwest Transmission Project TransWest Express Transmission Project West Side Tie Tres Amigas Western Spirit Clean Line Westside Tie 345/500 kV Wyoming-Colorado Intertie Project Zephyr WECC - Eastern Interconnect DC Tie Upgrade Project Projects highlighted in red, projects where Western Electricity Coordinating Council

Polling Tie Projects (1 to 1 Include/Exclude) What is the will of the group, Include or Exclude? Projects were originally in the “Include” list Southline Transmission Project (Afton-Apache) Comment: Project sponsor agrees this should not be included at this time Southline Transmission Project (Apache-Saguaro) Talega-Escondido / Valley-Serrano 500 kV Interconnect Comment: Project does not appear in CAISO transmission plan, and has not been submitted to CAISO as a “Merchant Project” Current status – Undecided – and seek input from RPCG What is the will of the group? Do we err on the side of caution and exclude? Get members thoughts. Western Electricity Coordinating Council

Final 2026 CCTA Project List Energy Gateway West: Bridger – Populus Energy Gateway West: Windstar to Jim Bridger Energy Gateway West: Midpoint – Hemingway Energy Gateway West: Populus – Midpoint Energy Gateway West: Populus – Cedar Hill – Hemingway Energy Gateway: Wallula – McNary 230 kV Centennial II: Harry Allen - Eldorado 500 kV I-5 Corridor Reinforcement Project (Castle Rock - Troutdale) Morgan-Sun Valley 500kV Line Path 8 Upgrade/Colstrip Transmission Upgrade Pawnee-Daniels Park Central Ferry – Lower Monumental Delaney-Palo Verde 500kV Line Delaney-Sun Valley 500kV Line Desert Basin - Pinal Central Devers - Colorado River 500 kV (DCR) Energy Gateway Transmission Project - Segment G (Sigurd - Red Butte 345 kV line) Hassayampa - North Gila 500kV #2 line Interior to Lower Mainland Transmission (ILM) Pinal Central-Tortolita - Pinal West-Pinal Central-Browning (SEV) West of McNary Reinforcement Project Group 2 (Big Eddy - Knight) Boardman-Hemingway 500 kV (B2H) Delaney - Colorado River 500 kV Transmission Project (Ten West Link) Energy Gateway South: Aeolus-Mona 500 kV If the previous slide gets unanimous agree to exclude… this will be the final 2026 ccta. If not, we will have to make minor changes. Blue text denotes under construction or in-service

Overall Feedback on Process Criterion 3 and 4 to be reviewed and/or refined in future planning cycles Definitions Thresholds Adjustments to “criteria” ? FERC Order 1000 planning based improvements? Other regulatory/state planning/policy drivers? Future meeting – June/July – modify CCTA 2028 process?! Western Electricity Coordinating Council

System Adequacy Planning Vijay Satyal – Staff Liaison Contact Information Colby Johnson System Adequacy Planning Office: (801)819-7662 cjohnson@wecc.biz Vijay Satyal – Staff Liaison Sr. Policy Analyst vsatyal@wecc.biz Western Electricity Coordinating Council