SALT LAKE CITY--(BUSINESS WIRE)--Questar Corporation (NYSE:STR) reported second-quarter 2015 net income of $40.6 million, or $0.23 per diluted share compared to second-quarter 2014 net income of $40.3 million, or $0.23 per diluted share. Adjusted earnings before interest, taxes, depreciation and amortization (Adjusted EBITDA) for the quarter were down 5% to $130.1 million compared to $137.3 million in the year-ago period. Return on average common equity (ROE) was 17.6% for the 12 months ended J