By SUE MANNING

Associated Press

LOS ANGELES (AP) -- California gas prices eased fractionally Wednesday after five days of staggering increases that saw prices closing in on $5 a gallon, but a Chevron refinery closure through the rest of the year might put a crimp in plans to reduce pump pain.

During the five-day price surges, gas went up about 50 cents a gallon.

The average price of regular Wednesday was less than $4.67 a gallon, down a half-cent from Tuesday, but it's still the highest price in the nation, the AAA Daily Fuel Gauge Report said.

The highest average price in the state was $4.75 in the San Luis Obispo, Atascadero and Paso Robles area. San Francisco's price was just over $4.73 a gallon, followed by San Diego at $4.71 and the Los Angeles area at $4.70.

State officials predicted prices would fall after Gov. Jerry Brown ordered early production of a winter fuel blend to replace costlier summer blends.

The spike in prices was driven by refinery disruptions, including a fire and a power outage, and corrosion problems in a critical pipeline, analysts said.

Many motorists and some lawmakers believe fraud might be more likely than a supply problem so there have been calls for Federal Trade Commission and the Department of Justice to investigate.

Brown moved to stunt the spike by ordering the California Air Resources Board to allow "winter-blend" gasoline to be sold in the state earlier than usual to increase supply. To reduce air pollution, California law requires that gas stations during warmer months use a special blend of fuel that is not widely available.

Early conversion was last needed in 2005 when supplies dwindled because of refinery disruptions caused by Hurricane Katrina.

California usually converts to the gas on Oct. 31. The fuel evaporates in heat more quickly than summer-blends, so sends more pollutants into the environment, especially in warm weather.

Air pollution regulators said they don't expect the state's air quality to suffer because of the early start, but the conversion could increase supply by 8 percent to 10 percent, the governor's office said.

One of the disruptions to the state's gasoline inventory occurred in August when fire forced the shutdown of the Chevron refinery in Richmond. Chevron said Tuesday the plant will remain closed through the end of the year.

Copyright 2012 The Associated Press.