PSO (a) Jointly-owned with nonaffiliated entities. Figures presented reflect only the portion owned by SWEPCo. The Arkansas jurisdictional portion of SWEPCo’s interest in Turk Plant is not in rate base. (b) In January 2020, management announced plans to close the plant at the end of 2026. (c) Knox Lee Unit 4 was retired in January 2019. Figures presented include Unit 4 in the total. (d) Knox Lee Unit 2 and Unit 3, Lieberman Unit 2 and Lone Star are scheduled for retirement in May 2020. (a) Weleetka Unit 6 was retired in March 2019. (b) Jointly-owned with AEP Texas and nonaffiliated entities. Figures presented reflect only the portion owned by PSO. (c) In September 2018, management announced plans to close the plant by October 2020. SWEPCo 45 Plant Name Units State Fuel Type Net Maximum Capacity (MWs) Year Plant  or First Unit Commissioned Mattison 4 AR Natural Gas 315 2007 Stall 3 LA Natural Gas 534 2010 Flint Creek (a) 1 AR Steam - Coal 258 1978 Turk (a) 1 AR Steam - Coal 477 2012 Welsh 2 TX Steam - Coal 1,053 1977 Dolet Hills (a)(b) 1 LA Steam - Lignite 257 1986 Pirkey (a) 1 TX Steam - Lignite 580 1985 Arsenal Hill 1 LA Steam - Natural Gas 110 1960 Knox Lee (c)(d) 4 TX Steam - Natural Gas 404 1950 Lieberman (d) 3 LA Steam - Natural Gas 242 1947 Lone Star (d) 1 TX Steam - Natural Gas 50 1954 Wilkes 3 TX Steam - Natural Gas 889 1964 Total MWs 5,169 Plant Name Units State Fuel Type Net Maximum Capacity (MWs) Year Plant  or First Unit Commissioned Comanche 3 OK Natural Gas 248 1973 Riverside, Units 3 and 4 2 OK Natural Gas 160 2008 Southwestern, Units 4 and 5 2 OK Natural Gas 170 2008 Weleetka (a) 2 OK Natural Gas 100 1975 Northeastern, Unit 1 1 OK Natural Gas 470 1961 Northeastern, Unit 3 1 OK Steam - Coal 469 1979 Oklaunion Power Station (b) (c) 1 TX Steam - Coal 105 1986 Northeastern, Unit 2 1 OK Steam - Natural Gas 434 1961 Riverside, Units 1 and 2 2 OK Steam - Natural Gas 901 1974 Southwestern, Units 1, 2 and 3 3 OK Steam - Natural Gas 451 1952 Tulsa 2 OK Steam - Natural Gas 325 1956 Total MWs 3,833