The Task Is a Giant One for Cleanup Forces : O’Melveny Park: Flooding is just the latest disaster to hit the popular 714-acre site in Granada Hills.

O’Melveny Park, known for its pristine vegetation and extensive hiking trails, has taken just about everything that Mother Nature could dish out--from a devastating brush fire, to drought, to a band of sheep that wandered into the park and gobbled up grass, flowers and saplings.

The latest disaster to hit the Granada Hills park occurred when rainwaters from last month’s storm rushed down Bee Canyon Creek and washed away six pedestrian bridges, flooded a Boy Scout campground and caused more than $500,000 worth of damage.

“It’s a setback every time we have a disaster there,” said Mary Ellen Crosby, chairwoman of Friends of the Park. “They work on it and another disaster hits.”

Burned branches and other debris resulting from the 1988 Porter Ranch brush fire clogged the creek that runs the length of the park, forcing fast-moving rainwater to jump the creek banks.

In one area, the force of the water dug a six-foot-deep gorge in what used to be a dirt access road. It snapped a pipe that supplied water for a fire hydrant, tipped over a cement water fountain and uprooted at least 25 trees.

Park officials said the 1988 fire also destroyed heavy vegetation, such as chaparral, that helps prevent mudslides. While the park is not as lush as it was before the fire, most park areas are green with grass, trees and wildflowers.

“I would say that probably the flood was intensified by the fact that there was a lot of underbrush and trees that were burned,” said Richard Ginevan, a chief park maintenance supervisor.

Ginevan said park officials are hoping that state and federal disaster relief money can be used to pay for the cleanup.

Mudslides and flooding also caused an estimated $300,000 worth of damage to the small parks and trails that wind throughout the residential neighborhoods in the nearby Porter Ranch area.

Park officials have worked for the past week to clear out mounds of mud and branches at O’Melveny--Los Angeles’ second largest city park--and will probably continue to do so for another two or three weeks. They said city officials want to concentrate cleanup efforts in the Sepulveda Basin, where flood damage was heaviest.

“It was just getting back to normal,” Ernest Mathis, a park maintenance supervisor, said as he surveyed the damage at O’Melveny. “Quite a few people use this on weekends and that is why we want to get it back in shape as soon as possible.”

Mathis said the park is still open to visitors, but park officials are warning that some hiking trails may be dangerous and inaccessible.

The 714-acre park, which includes about 10 miles of hiking and equestrian trails, was established after John O’Melveny, the senior law partner in the firm of O’Melveny & Myers, donated most of the land to the city in 1973.

But the Dec. 10, 1988, Porter Ranch fire that destroyed or damaged 40 homes and burned 3,200 acres, scorched nearly all of the park’s trees, shrubs and wildflowers, causing more than $300,000 worth of damage. Park officials decided late that month to allow the ashen hillsides to regenerate naturally and did not seed the park with ryegrass as they had in some hillsides near residential areas.

“When you lose all that in a fire, you don’t regain it all for about 10 years and that is with a normal rainfall,” Mathis said.

He said the park’s population of small animals, such as rabbits, are just now returning to the pre-fire strength. The park is also home to rattlesnakes, red tail hawks and a few mountain lions, Mathis said.

A less destructive natural disaster struck the park two years later when 200 sheep that had been grazing on private property north of the park wandered through a hole in a fence and began munching on sprouting vegetation. Among the victims of the woolly beasts were 100 young pines and cedars planted by nearby elementary school students.

The drought has also played a role in hampering the regrowth of chaparral and other native vegetation. But park officials said a strong rainstorm last March helped rejuvenate the park’s plant life.

The most recent flooding was grim news for longtime park users.

“It’s unfortunate because I used to run up here,” said Stephen Wahlen, a Canoga Park resident, as he overlooked a washed-out bridge along Bee Canyon Creek. “It’s such a nice park.”

Robert Gunn, a psychologist who lives across the street from the park, said he has hiked its trails almost daily for 25 years.

“It was devastating to say the least,” Gunn said of the flood damage. “I thought the park was faring fairly well.”