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

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

Current Ownership Structure Navajo Southern System Navajo Switchyard Navajo – Moenkopi Line Navajo – Dugas – Morgan – Westwing Line Moenkopi – Cedar Mtn. - Yavapai – Westwing Line APS 14.0% LADWP 21.2% NVE 11.3% SRP 21.7% TEP 7.5% USBR 24.3% APS 24.7% SRP 38.3% TEP 13.3% USBR 23.7% Navajo Western System Navajo – Crystal – McCullough Line LADWP 48.9% NVE 26.1% USBR 25.0%

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