Questar Corp. will spend $517 million in its 1998 capital budget, marking the largest single-year capital spending program in the company's history.

Questar's board of directors authorized the $188 million capital increase Tuesday, according to a company press release. R.D. Cash, Questar's chairman, president and chief executive, said the higher spending projection "recognizes our growing success in finding high-quality investment opportunities that will boost our performance."Cash said $243.8 million of the capital budget will go toward Questar's market resources arm, which includes gas and oil exploration and production, gas gathering, energy marketing and trading and retail services. Another $228.1 million will go toward regulated services, including interstate gas transmission and storage and retail gas distribution.

Salt Lake-based Questar will fund the 1998 capital program through short- and long-term debt.

"With our strong cash flows and balance sheet, we do not foresee the need to conduct an equity offering in the near term in order to finance our growth projects," Cash said in the release.

The company said the Questar Gas retail gas-distribution subsidiary will require about $65 million in capital investment in 1998 due to strong growth. The utility's customer base grew at a 3.5 percent rate for the 12 months ended June 1998.

Also Tuesday, Questar's board approved a 16.5-cent quarterly dividend payable Sept. 14 to shareholders of record on Aug. 21. The dividend is the same as the previous quarter's and 5 percent higher than last year's.