For Most Part, O.C. Weathers Storm Handily : Rain: South County is hit the hardest, but scattered traffic accidents are the only major problems of what forecasters expect is the last big rainfall of a very wet season.

Orange County endured with surprising ease Tuesday what weather officials called the season’s last major storm, which nevertheless pummeled San Clemente and Laguna Beach with an inch of rain and triggered more than 70 traffic accidents countywide.

With no more than a quarter inch of rain falling anywhere else in the county, the downpour saved its fiercest punch for parts of South County, including San Clemente, which also had the day’s worst traffic accident, involving five vehicles.

In what the California Highway Patrol called a chain-reaction pileup, a Dodge pickup collided with a semi truck, whose fuel line ignited as it jackknifed across several lanes of northbound Interstate 5 shortly after 9:30 a.m. near the Avenida Pico exit.

Two lanes were closed for about an hour.

“The semi was coming up behind him and jackknifed, striking one of the other vehicles,” CHP spokesman Bruce Lian said. “The semi then caught fire when its diesel fuel line ripped apart and ignited. We were real lucky we had only minor injuries and damage to just two of the vehicles. Real lucky.”

The driver of the Dodge pickup, Matthew Pohl, 23, of Fallbrook, is under investigation, Lian said, for his apparent role in the accident.

Although two other accidents involving big-rig trucks occurred Tuesday morning on the Orange Freeway, the San Clemente pileup was by far the worst among weather-related accidents, CHP officials said.

Elsewhere, county officials and law-enforcement officers were pleasantly surprised by how well the area held up in what weather forecasters said was probably the last major rainfall of the season, one of the wettest on record.

“What we’re seeing on the near and far end looks like the last rain episode for Southern California for quite a while,” said Curtis Brack, a forecaster with WeatherData Inc. “As far out as we can see, which is five to seven days, at least, it looks quite dry.”

Laguna Beach, which was devastated during the heavy rains of early January, felt no need to even open its storm center Tuesday, much less evacuate residents who continue to fear mudslides.

Flood control channels--which ruptured in early January, sending torrents of water cascading down the streets of Garden Grove, Buena Park and Westminster--held up fine, as did the Leisure World retirement village in Seal Beach, which sustained damage in earlier storms.

Brack blamed the region’s unseasonably wet 1995 on the El Nino effect, which he said should be winding to a close.

“All of this has been influenced by El Nino’s warmer-than-normal waters off the West Coast, down toward Mexico and South America, which has greatly affected our weather patterns,” he said. “It’s been supplying more moisture and high-energy heat to the atmosphere, which in a nutshell is why you’re getting all this rain on the West Coast. But El Nino is pretty much over now.”

The wet weather, which already has inflicted millions of dollars in damage on financially strapped Orange County, contributed to the major accidents involving big rigs.

One big rig was twisted into an “L” shape after it attempted to brake early Tuesday on the northbound Orange Freeway near the Katella Avenue exit. No injuries were reported.

Another big rig stalled in the middle lane of the southbound Orange Freeway about 8 a.m., just south of the county boundary, delaying traffic but sparing drivers from injuries.

Times staff writer Yvette Cabrera and Times correspondent Frank Messina contributed to this report.

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Storm Totals Orange County received scattered rainfall Tuesday, with southern areas receiving the brunt of the storm. Tuesday8s rain, from midnight to 4 p.m.

City Inches Anaheim 0.10 Dana Point 0.93 El Toro 0.28 Laguna Beach 1.00 Newport Beach 0.75 San Clemente 1.00 San Juan Capistrano 0.83 Santa Ana 0.17

Year- to- Date Rain Santa Ana readings, as of 4 p.m. Tuesday, for rain season beginning July 1:

Period Inches Season 24.38 Last year 12.08 Normal 11.97

Source: WeatherData Inc.