PORTLAND, Ore. (AP) -- Starting next month, customers of the state's largest natural gas utility could see rates increase by 14 percent.

NW Natural delivered its final gas cost estimates Friday along with Cascade Natural Gas and Avista -- the state's two other investor-owned gas utilities.

The requests are lower than estimates given state regulators earlier because natural gas prices have dropped in recent months. Earlier this year, for example, NW Natural had said its rates might rise as much as 40 percent.

The short-term spot price of Canadian and Rockies natural gas has plummeted in the past two months after reaching a high alongside crude oil prices in July.

However, utilities don't buy much of their gas supply on the spot market, and their projected prices only partially reflect the recent steep decline.

Oregon state regulators are expected to set rates, effective Nov. 1.

Currently, the commodity cost of fuel makes up about two-thirds of a customer's gas bill. The utilities make no markup on the gas, simply passing through their cost to consumers.

The projected rate increases differ among the utilities because each uses different financial strategies to hedge market risk and each has a different set of fees and refunds flowing through rates at any given time.

Cascade says its central Oregon customers can expect a 5.4 percent increase.

Avista says its customers in southern Oregon will likely see prices drop by 4.1 percent.

NW Natural has 650,000 customers in Oregon and Washington state, where it is seeking a 20 percent rate increase.