Spokane, WA-based Avista Corp.’s combination utility filed with Washington state regulators Monday, seeking rate increases for its natural gas and electric operations to recover costs of bolstering infrastructure to serve 234,000 electric and 147,000 natural gas customers in the state.

The general rate increase requests were made to the Washington Utilities and Transportation Commission (WUTC) — a $6.2 million, or 4%, annual hike for gas service and a $38.3 million, or 8.7%, increase for retail electric customers. Increases in the average residential customer monthly gas and electric bills would be 5.1% and 9.3%, respectively. Under state law, the WUTC has 11 months to act on the request.

A major part of the gas hike seeks to recover Avista Utilities’ cost of a portion of the gas it stores in the Jackson Prairie storage facility in southwest Washington. “The addition of underground storage capacity this year will allow Avista to purchase and store natural gas during the months when market prices are generally lower and use the gas to serve customers during winter months when market prices tend to be higher,” a utility spokesperson said.

The rest of the hike is to cover Avista’s upgrading of sections of its existing pipelines and related equipment used to deliver gas to its customers in the eastern half of the state.

On the electric side, Avista told regulators it plans on investing nearly $250 million in its infrastructure this year to ensure reliability and meet customer demand by replacement of “aging equipment, including power lines, poles, substations, transformers and related equipment for its transmission and distribution systems.” In addition, it is upgrading generation-related facilities.

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