U.S. retail gas prices declined 2.5 cents over the last week to $2.87 a gallon, the lowest level in six weeks, the U.S. government said on Wednesday.

The pump price for regular unleaded gasoline is still 77 cents higher than a year ago, based on the Energy Information Administration's weekly survey of service stations.

The drop in the latest pump price would have been steeper, but in a rare move the EIA revised up the prior week's national price by almost a penny after it received incorrect fuel cost information from stations in Los Angeles.

Click here for FOXNews.com's Energy Center.

"We got bad numbers reported to us," an EIA spokesman said. Agency officials realized there was a problem after it noticed its L.A. fuel prices were very different from the pump prices reported by the AAA auto and travel group.

Once the correct data was sent, the EIA also revised up the previous week's average price for gasoline in Los Angeles by 15.3 cents, and that pushed up the national price.

In this week's survey, which was delayed to get the correct information, the average pump price in Los Angeles fell 4.1 cents to $3.34 a gallon, the highest for any city.

The EIA's weekly survey reflects prices at about 800 stations nationwide, including 128 on the West Coast. The agency refused to say how many L.A. stations are surveyed.

The West Coast had the most expensive gasoline by region, with the price down 4.4 cents to $3.21 a gallon.

The Gulf Coast states had the cheapest gasoline at $2.74 a gallon, down 4.6 cents. Among major cities, Cleveland again had the best pump price at $2.71, down 5.6 cents.

Separately, the average diesel fuel price paid by truckers fell a slight 0.6 cent over the last week to $2.88 a gallon, up 72 cents from a year earlier, the EIA said.

Truckers on the West Coast paid the most for diesel at $3.16 a gallon, down 1.4 cents. The Gulf Coast region had the cheapest diesel at $2.80 a gallon, down 0.3 cent.

Meanwhile, U.S. oil companies have taken steps to try to limit any gasoline supply disruptions that may be caused by hurricanes this summer.

Retail pump prices soared far inland last year after hurricanes Katrina and Rita shut many Gulf Coast refineries that made gasoline and also knocked out power to pipelines that moved the fuel to cities in the South and up the East Coast.

Government and industry officials warned that consumers should not fill up their cars and trucks with gasoline right before the next storm hits in order to avoid the high fuel prices that would likely follow, because the distribution system could not handle the spike in gasoline demand.

If necessary, strong gasoline imports will help make up the loss from storm-related fuel supply disruptions, according to the head of the American Petroleum Institute.

"We are bringing in (motor fuel) at record levels right now and we have received no indication that record levels of gasoline wouldn't continue to flow into this market," API President Red Cavaney said Tuesday at a briefing on how the U.S. oil industry is better prepared to deal with hurricanes.

Visit FOXNews.com's Energy Center for more information.