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Jerry Gaona guides his horse each day across a footbridge high above the Los Angeles River, barely mindful of the trash, graffiti and stench below. Or of its brutal concrete straitjacket.

“It’s called the L.A. River. My feeling is, ugh — it’s just dirty, dingy, gross,” said Gaona, 26, of Burbank, from atop his palomino paint as a shallow river of wastewater flows past the Los Angeles Equestrian Center near Griffith Park.

“If they could make bike paths, with grass, with lakes and make it look like a natural river . . . the potential is great. It could be our Central Park — a place where people could go to be refreshed.”

City officials seek just such community input on the Los Angeles River in order to fashion a grandiose plan to turn 32 miles of drab flood-control channels into a meandering river walk of parks, paths, restaurants and housing.

Renewing the long-neglected river, they say, would restore native habitats and wildlife, improve flood control and respond to a federal order to clean up polluted waters now spilling into the Pacific.

The $3 million Revitalization Master Plan — to be drafted by experts on urban river redevelopment based on community input from 18 public hearings throughout the city — would map 250 feet along each bank for potential redevelopment.

Its cost: “$1 billion, easy,” in county, state and federal dollars, said City Councilman Ed Reyes, who chairs a committee on L.A. River renewal.

“We treated it as if it didn’t exist. We thought of it as a sewer and we treated it as a sewer,” said Reyes, standing within a verdant section of the river near Taylor Yard where he used to swim and catch catfish as a kid.

“The city has a choice: to approach it as a sewer — or [as a] river.

“Smart cities have turned a throwaway sewer into a river asset. The real mission here is to clean up the urban slobber.”

The once-pastoral river, which historically ran nearly dry during summer, became a torrent during winter rains. After a disastrous flood in 1938, the U.S. Army Corps of Engineers built the flood-control system that cemented much of its beauty for 51 miles, from the San Fernando Valley to Long Beach.

Nowhere is the river more stark than at the L.A. River’s headwaters in Canoga Park, where Arroyo Calabasas and Bell Creek form a concrete abutment behind Canoga Park High School.

Green slime covers a concrete river bottom littered with shopping carts, broken chairs and plastic bottles. An odor of fetid algae fills the air.

“It’s a mess,” said Joe Linton, director of outreach for Friends of the Los Angeles River, one of many groups to advocate for river cleanup and restoration. “This isn’t where I take people on walks. The herons and egrets avoid this section, too.”

Restoration proponents blame much of the river’s funk on a confusing jumble of jurisdictions that manage its various legs, such as the U.S. Army Corps of Engineers and the Los Angeles County Department of Public Works.

Army Corps officials say that a lean budget and an emphasis on flood control limit how much trash and slime they can scrape out of the river bottom. The federal agency owns, operates and maintains 38 miles of the 51-mile river.

Linton, whose guide “Down by the Los Angeles River” will be published next month, conducts tours of such pristine sections as the Sepulveda Basin, where the river — the only section devoid of concrete — follows a natural course flanked by willows, mule fat and nonnative bamboo.

What makes the Valley unique is the grass-roots cleanup along its banks, where the Village Gardeners of Sherman Oaks and Ernie La Mere fashioned pockets of paradise in Sherman Oaks, unlike the sprawling state parks being developed at Taylor Yard and the Cornfields downtown.

A greenway was also recently built at state expense in Studio City.

“It’s the untold story: The Valley is the site of do-it-yourself river reclamation,” Linton said. “One person, or groups of neighbors, went down to the river and said, `My, I think I’ll plant some geraniums.’

“They didn’t wait for government.”

Two years ago, real estate agent Abby Belkin became so smitten with the Village Gardens, a community-planted park in Sherman Oaks, that she bought a riverfront town house. But her delight soon turned to disillusionment.

“I see Jeeps driving the river all the time — driving by all the trash,” said Belkin, 56. “There was a chair in there . . . it was there for months.”

Master planners hope to instill more pride in the river by stitching such piecemeal parks into a greenway magnet for economic development. Concrete banks could be terraced or torn down, where safe, and landscaped. Lakes could be created through inflatable dams. New homes and businesses could be turned to face the river.

Restoration could take decades.

“It took a long time to screw it up and it’ll take a long time to turn it into something amazing,” said Lewis MacAdams, founder of the Friends of the River, who 20 years ago helped spawn the L.A. River restoration movement.

“I want to see the steelhead trout come back. That’s my dream.”

Said City Councilman Tom LaBonge, a member of the river restoration committee: “It might cost a lot of money, but it’s worth a lot of money.”

Proponents of renewal say the Valley will be key to river restoration, to be planned in five segments from Canoga Park to Boyle Heights.

As Taylor Yard in Cypress Park is being turned into soccer fields, baseball diamonds and native habitat, parks can also be built in the Valley to accommodate a burgeoning population.

“I call this the new frontier,” Councilman Reyes said amid the construction of the 40-acre park within his district. “If it’s happening here, why can’t it happen in the Valley, where they want it?”

For inspiration, planners point to such cities as San Antonio, whose River Walk has become synonymous with the city, and to Denver, whose South Platte Initiative transformed 11 miles of industrial blight into a contiguous greenbelt of parks.