Navajo Transmission System Four Corners Wind Resource Center

Navajo Transmission System Four Corners Wind Resource Center April 25, 2017

Transmission Systems and Ratings Western Electricity Coordinating Council (WECC) Path Rating Process: • “Peer Reviewed” process for single lines or paths • Sets long term capability rating – cannot be diminished by future lines • Subject to re-rating for changed conditions • Current ratings for Navajo Transmission Elements: • Path 49: 10, 100 MW (2, 000 MW allocated to Navajo-Crystal line) • Path 51: 2800 MW

Transmission Systems and Ratings (Con’t) No. American Electric Reliability Council (NERC): • Total Transfer Capability (TTC): The amount of power that can reliably be transmitted across a line or path (equal to WECC Path Rating if process performed for that element) • Available Transfer Capability (ATC): TTC less committed uses. • TTC and ATC are calculated for discrete time periods – yearly, monthly, weekly, daily, hourly

Glen Canyon Crystal Marketplace Navajo Four Corners Mead Mc. Cullough Eldorado Moenkopi Path 51 Cedar Mtn. Arizona EHV Transmission System 500 k. V 345 k. V Colorado River 230 k. V Navajo Western Navajo Southern North Gila Cholla Sugarloaf Yavapai Dugas Coronado Springerville Morgan Westwing Rudd Kyrene Palo Verde Hassayampa PPK Silver King Jojoba Gila River Pinal West Duke Greenlee Pinal Central Saguaro EOR or Path 49 South Vail

Current Ownership Structure Navajo Southern System Navajo – Dugas – Morgan – Westwing Line Moenkopi – Cedar Mtn. - Yavapai – Westwing Line Navajo Switchyard Navajo – Moenkopi Line • • • APS LADWP NVE SRP TEP USBR 14. 0% 21. 2% 11. 3% 21. 7% 7. 5% 24. 3% • • Navajo Western System Navajo – Crystal – Mc. Cullough Line • LADWP 48. 9% • NVE 26. 1% • USBR 25. 0% APS SRP TEP USBR 24. 7% 38. 3% 13. 3% 23. 7%

Thank You! Charlie Reinhold, reinhold@ctcweb. net 208 -253 -6916