Investor Presentaiton

Customer Growth and Accelerated Replacements Drive Growth High near-term growth Expected near-term growth driven by customer additions, accelerated replacement programs and general system betterment capital expenditures Increased diversification into high growth areas such as Washington (6th largest regional economy in the U.S., among the highest median household incomes in the U.S.) Projected Rate Base Growth (C$ billions) ■Rate Base Replacements ~$5.2bn ■New business Other utility $2.8bn ~$8 bn AltaGas YE20171,2,3 Utility capex to 20213,4 Gross combined rate base 20215 1 As of December 2017 2 WGL extrapolated to calendar year end 2017 based on FY2016 rate base and a CAGR of 9.0% 3 WGL figures converted to Canadian C$1.26 / US $1.00 4 WGL Management estimates 5 Gross rate base excludes depreciation See "forward-looking information" 12

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