BAKER CITY — Gasoline prices in Northeast Oregon are the among the lowest in the state as refinery maintenance and other factors push prices higher in most of Oregon and nation.

Oregon’s average price for a gallon of regular unleaded has risen by a dime over the past week, to $3.89 on Thursday, March 7.

The national average for that day was $3.39.

Prices are lower than the Oregon average in all counties in the northeast corner.

The cheapest gas among Oregon’s 36 counties is in Baker and Malheur counties, both of which had an average price of $3.48 per gallon on March 7.

Other county averages as of Thursday:

• Gilliam: $3.59

• Morrow: $3.63

• Umatilla: $3.72

• Union: $3.73

• Grant: $3.73

• Wallowa: $3.86

Oregon’s highest average price was in Curry County, at the southwest corner of the state, at $4.18.

Multnomah County, which is the state’s most populous county and includes Portland, had the second-highest average at $4.05 per gallon.

Prices are likely to increase for the next several weeks due in part to a temporary decline in supply, said Marie Dodds, public affairs officer for the AAA auto club in Oregon and Idaho.

Factors that have reduced gas supplies include maintenance at refineries in the San Francisco Bay area, some planned and some not, as well as maintenance on locks on the Columbia River that has prevented fuel barges from moving up the river, Dodds said.

Work on the locks is expected to end by April 1, she said.

Gas prices also tend to increase this time of the year due to rising demand as people travel for spring vacation, Dodds said.

Oregon’s average price has increased by 29 cents over the past month. The national average has risen by 25 cents.

Oregon’s average is the fifth-highest among states. California has the highest average, at $4.86 on March 7, followed by Hawaii, $4.71, Washington, $4.16, and Nevada, $4.09.

Idaho’s average is $3.28.