A number of natural gas utilities across the United States have asked state regulators for a decrease in their rates as the winter heating season approaches, citing an oversupply of gas from shale gas development.

Utilities are seeking an estimated 5-6% decrease in their natural gas rates. Delmarva Power, a gas and power utility subsidiary of Pepco Holdings Inc., has filed two gas rate changes with the Delaware Public Service Commission that if approved would result in an overall monthly bill decrease of $8.18, or about 5.4% for typical residential customers who use 120 Ccf (100 cubic feet) of gas per month. Both of the proposed rates would take effect at the start of the winter heating season on Nov. 1.

This represents the third straight year of gas cost reductions for customers, according to Delmarva, which supplies gas to about 124,000 customers in northern Delaware and electric service to 501,000 customers in Delaware and the Delmarva Peninsula.

In November 2012, there was a reduction of $23.79 per month, or 14.4%, for a residential customer using 120 Ccf. Delmarva said commercial and industrial customer rates also would decrease if its latest regulatory filing is approved, but the monthly bill impact among those customers will vary with usage.

On the other side of the country, Spokane, WA-based Avista Corp. is seeking a decrease of 5.5% in natural gas rates for its 96,000 Oregon customers, effective Nov. 1. If the request is approved, an Avista residential user using an average of 48 therms a month could expect their bill to decrease by $3.27, or 5.6%, for a revised monthly bill of $54.73 beginning at the start of this winter, Avista said.

About 55% of an Avista natural gas customer’s bill is the combined costs of purchasing gas on the wholesale market and transporting it to Avista’s system. These costs fluctuate based on market prices, and Avista does not mark up these costs, the utility said. The remaining 45% covers the cost of delivering the natural gas.

Avista Utilities is the company’s operating division that provides electric service to 362,000 customers and natural gas to 322,000 customers in eastern Washington, northern Idaho and parts of southern and eastern Oregon.

Questar Gas asked Utah regulators to lower typical homeowner’s annual bill by about $10, or 80 cents/month. The request came only a few months after Questar sought a $19 million increase in its general rates to cover operating and business costs, which would add $1.36 to a customer’s monthly bill.

If both requests are granted by the the Utah Public Service Commission, Questar gas customers will pay 56 cents/month more for natural gas this winter, a spokesman for the company said.

“Abundant natural gas supplies continue to hold down the price of natural gas,” said Craig Wagstarr, executive vice president of Questar Gas.

Vermont Gas, the state’s only gas company, said it plans to cut its gas rate by nearly 6% effective Nov.1. The company, which serves northwestern Vermont, said its customers are benefiting from price cuts being offered by suppliers as a result of the boom in shale gas development.