The state Public Utilities Commission has approved a $9.5 million interim rate increase for The Gas Co. that will raise rates across the islands.

The increase, which is the company's first adjustment since 2001, would add anywhere from $4.08 to $7.81 a month to the average residential gas bill, said Stephanie Ackerman, vice president of public policy and communications for The Gas Co. Customers on Maui, Kauai and the Big Island would pay about 14 cents a day more, while customers on Molokai would pay 25 cents more, and customers on Lanai and Oahu about 26 cents more, Ackerman said.

The new rates will affect 35,000 utility customers — about half of the company's 70,000 customers, she said.

Utility customers are typically those who are served by an underground pipeline.

Nonutility tank customers and bottled-gas customers will not be affected by the increase.

The new rate, which will be applied tomorrow, will remain effective until the PUC issues a permanent order. If the PUC ultimately recommends a lower rate, The Gas Co. would have to reimburse consumers, Ackerman said.

“;We are pleased with the outcome of the rate case,”; said James Hooke, chief executive of Macquarie Infrastructure Co., parent company of The Gas Co. The interim decision “;is fair and recognizes the substantial increase in the costs associated with meeting the energy needs of the business' utility gas consumers over the past eight years,”; Hooke said.

The Gas Co. originally had filed an application for a $12.5 million rate adjustment with the PUC last August. In its application, the company cited the need to recover operational and maintenance costs, as well as capital investments, renewable energy projects and compliance with new federal regulations, as reasons for the rate increase.

The interim increase brings The Gas Co. an 8 percent return on its base rate and represents an 11 percent increase in revenue, Ackerman said.

FEELING THE PINCH

» Utility customers affected: 35,000
» Overall increase: $9.5 million, which represents an 8 percent return on investment for The Gas Co.
» Average residential bill on Oahu: $55.20 based on usage of 14 therms

ADDITIONAL COST
» Oahu: $7.67 per month, or 26 cents a day
» Maui: $4.07 per month, or 14 cents a day
» Molokai: $7.44 per month, or 25 cents a day
» Kauai: $4.08 per month, or 14 cents a day
» Big Island: $4.11 per month, or 14 cents a day
» Lanai: $7.81 per month, or 26 cents a day
Source: The Gas Co.