NEW YORK (TheStreet) -- When will the Federal Reserveraise interest rates? If you are invested in utility stocks, here's a tip: stick with Dallas-based natural gas distributor Atmos Energy (ATO) - Get Report, which will continue to grow no matter when Fed Chairwoman Janet Yellen makes her move, said Ryan Kelley, portfolio manager for the Hennessy Gas Utility Fund. 

"They will continue to see natural gas move through their system and continue to grow at a small pace every year," said Kelley.

Shares of Atmos Energy, which yields 2.8%, are up 4% year to date. The Hennessy Gas Utility Fund has fallen 12% so far in 2015, according to fund-tracker Morningstar, primarily due to worries about rising interest rates. The $1.6 billion fund has a trailing 12-month yield of 2.6%.

The fund also holds Atlanta-based AGL Resources (GAS) , which yields 3.3%. AGL is being bought out by Southern Company (SO) - Get Report for $66 in cash per share or $8 billion.

"Southern Company is getting a very good company that has performed well for many years," said Kelley. "If Southern Company stays in the index we will continue to own that stock as well."

Kelley's fund also owns shares of Kinder Morgan (KMI) - Get Report, which are down 30% so far this year. The pipeline giant yields a healthy 6.5% because of the downturn in the stock. Some on Wall Street question whether the company can grow or even maintain that yield. Kelley, however, believes Kinder Morgan's coupon is secure.

Finally, Kelley holds New Jersey Resources (NJR) - Get Report in his fund. Shares of the northeastern utility, which yields 3.4%, are down 5.3% thus far in 2015. "They've raised dividends twice and have a 22 year history of raising dividends," said Kelley, adding that the company's wholesale services division is not adequately appreciated on Wall Street but is performing nicely this year.