National Fuel is cutting customer bills by 6.7%.
The company says the adjustment is being made because of a decrease in the market price of gas due increase Marcellus shale gas production. Gas supply charges are passed along to customers dollar for dollar.
Last month, the company forecast rising gas prices later this year. But market prices have declined since that December forecast.
National Fuel serves 209,000 customers in 14 counties in northwestern Pennsylvania.