Investor Presentaiton

L KALISPELL MISSOULA BUTTE GREAT ANFALLS HELENA HAVRE MONTANA BILLINGS BOZEMAN About NorthWestern LO 5 South Dakota Operations Electric 63,900 customers 3,622 miles - transmission & distribution lines 411 MW nameplate owned power generation Natural Gas 48,000 customers 1,766 miles of transmission and distribution pipeline ABERDEEN YELLOWSTONE NATIONAL PARK SOUTH DAKOTA HURON Montana Operations Electric 384,700 customers 24,877 miles - transmission & distribution lines 871 MW maximum capacity owned power generation Natural Gas 203,700 customers 7,057 miles of transmission and distribution pipeline 17.75 Bcf of gas storage capacity Own 43.1 Bcf of proven natural gas reserves NEBRASKA BROOKINGS MITCHELL YANKTON- NORTH PLATTE□ GRAND ISLAND KEARNEY D Thermal Generating Plants Nebraska Operations Natural Gas 42,700 customers 813 miles of distribution pipeline Electric Wind Farm Natural Gas Hydro Facilities Data as of 12/31/2020 Natural Gas Reserves Peaking Plants NorthWestern Energy Delivering a Bright Future

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