SALEM, Ore. -- Starting this week, petroleum retailers in nine counties in Northwest Oregon will be required to sell a blended fuel that is 10 percent ethanol (E-10).

The rest of the state will join them over the next nine months, in a phased-in implementation of the state's new renewable fuel standards, the Associated Press reports. 

Under a law passed last year by the legislature, the renewable fuel standard for ethanol kicks in when Oregon's ethanol production has the capacity to reach 40 million gallons a year.

The state achieved that goal last summer when Pacific Ethanol began producing at the Port of Morrow.

As of Jan. 15, the blended fuel is mandatory in Multnomah, Clackamas, Washington, Clatsop, Columbia, Tillamook, Yamhill, Polk and Marion counties. Portland had its own requirement for ethanol-blended fuel already in place.

By April 15, Linn, Lane, Benton, Lincoln, Douglas, Coos, Jackson, Josephine, and Curry counties will join the effort. Finally, by Sept. 16, all counties east of the Cascades will complete the full statewide implementation.

"The consumer should see minimal difference in mileage or the performance of their vehicle with the new fuel standard," said Russ Wyckoff, administrator of the Oregon Department of Agriculture's Measurement Standards Division.

Older vehicles that already may have some water contamination in their tanks may be affected by the change, he said. And motorists may need to change a fuel filter soon after the ethanol-blended product is put into the tank for the first time.

Advocates of blending gasoline with ethanol say it helps the environment, reduces dependency on foreign oil and, hopefully, will drop the price of motor fuel.

Another large-scale ethanol plant is planned at Clatskanie, Wyckoff said. Between the two plants, the majority of ethanol needed to supply the state eventually could come from local production. Other ethanol plants are on the drawing board at the Port of Morrow and in Stanfield.