Intermountain Gas Company customers received their sixth consecutive decrease in gas rates due to a decline in the cost of gas the company buys for its customers and increased gas supply.

The decrease will come in two components: a reduction in monthly bills that went into effect Monday as a result of the lower gas prices and a one-time bill credit in December. Combined, those adjustments result in a decrease of 7.1 percent for the average customer, according to the Idaho Public Utilities Commission.

For residential customers who use natural gas for both water and space heating rates will reduce by 3.1 percent or about $1.51 per month. Rates for residential customers who use natural gas for space heating only will decrease 0.4 percent or about 17 cents a month. For commercial customers, rates will decrease 3.1 percent, or about $6.46 per month.

Intermountain Gas also will give a one-time credit of $3.7 million to customers in December as a result of credits that accrued before the purchased gas cost adjustment last February.

For residential customers who use natural gas for both space and water heating, the one-time credit would be about $29.85. Residential customers with gas space heating only would get a credit of about $19.40. Commercial customers would get about $129.80.

The PUC commission said the credit would help customers during a time of year when natural gas bills are highest. “Instead of embedding the value of the credit in rates throughout the coming year, the single credit method will allow customers more immediate rate relief during a time period when natural gas usage is typically nearing its peak,” said the commission in a press release.