21 Miles of Walls Proposed Along River Channels : Flood control: Plan may also ease restrictive building and insurance requirements. Critics say it’s environmentally harmful.

The cloak of concrete that has for decades shielded the Los Angeles River channel promises to creep even higher under a federal flood-control project that is earning cheers from city officials and hisses from river advocacy groups.

As part of a $379-million project to harness floodwaters along the Rio Hondo and Los Angeles rivers, the Army Corps of Engineers is proposing to erect concrete containment walls atop the river levees. Ranging in height from a foot to nearly 9 feet, the walls would extend for 21 miles along the sides of the Rio Hondo and the lower reaches of the Los Angeles, running from South Gate to the ocean.

Federal engineers favor the walls as the most efficient way to hold back the most powerful of floodwaters, which, if not contained, might spread over an estimated 82 square miles in Long Beach and Southeast Los Angeles County, inundating an estimated 500,000 people and 142,000 buildings.

The project would also eliminate the need for restrictive building and insurance requirements that have been imposed in the flood plain. “We support it strongly,” Long Beach Public Works Director Ray Holland said of the corps proposal. “We’re affected in a major way by flooding.”

But to some environmentalists, the flood barriers would be another Berlin Wall, sealing off the surprisingly abundant river life that survives amid the concrete.

“This project has no environmental consciousness at all,” charged Lewis MacAdams, whose organization, Friends of the Los Angeles River, opposes the wall project. “It’s a 1930s solution. . . . The corps can’t think other than concrete.”

Bob Sulnick, executive director of American Oceans Campaign, an environmental organization, agreed. “The idea of trying to box (the river) in and restrict it is the wrong thing to do from an ecosystem point of view.”

Instead of erecting concrete parapets that will attract graffiti and block views of the birds that flock to some portions of the waterways, MacAdams said the corps should turn to more natural methods of flood prevention.

Tear up the rivers’ concrete bottom to encourage water seepage into the ground, he urges. Then widen the channel upriver and create drainage basins on abandoned industrial property near northern portions of the Los Angeles River.

Nice as all that may sound, it simply isn’t practical, insist the wall’s proponents.

“There are situations where (channel widening) can be done, but I don’t think the lower L.A. River is one of them,” said Michael Anderson, who heads the drainage planning section of the Los Angeles County Department of Public Works.

“I don’t believe those groups have identified the social and economic impact of removing buildings along 21 miles (to widen the channel). The parapet walls to me are a good compromise,” he said.

Moreover, Anderson said, widening the river in less developed northern stretches would not help handle floodwaters downstream because so much storm drainage is discharged into the river in its lower reaches.

Anderson and corps spokesmen said they hope to screen the wall with plantings and would also raise portions of the levee--on which a bicycle path and maintenance road run--so that river views would not be blocked.

Although much of the funding has been authorized by Congress, the project is still under review and the money has not yet been appropriated. If approved, construction would likely begin in early 1995.

According to corps plans, about 44% of the walls running along the lower Los Angeles River would be between 2 and 4 feet tall, a few stretches would only be a foot high, 29% would be 4 to 6 feet high and 11% would be between 6 to 8 feet. Wall heights along the Rio Hondo would also vary, with a few portions approaching 9 feet.

The walls would account for half of the project’s $379-million price tag, with the rest of the money paying for the elevation of highway and railroad bridges and some channel widening.