No Concrete Answers to Ventura Flooding : Environment: Unlike the L.A. River, lining the waterway is not an option. Experts say only fail-safe method is to forbid building in flood plains.

VENTURA — The flash flooding of the Ventura River that inundated a recreational vehicle park during February’s storms probably could have been prevented by boxing the waterway in concrete, many experts agree.

Clearing vegetation in the river also might have reduced the chance that the river would jump its banks, they added.

But scientists and government officials say that even the most aggressive brush clearance measures could not have guaranteed protection in a storm as intense as the Feb. 12 rain that hit the saturated Ventura River watershed with nearly an inch of rainfall an hour for five hours.

Replacing natural river systems with concrete has not been an option to control floods in most cases since the advent of environmental awareness and state and federal regulations in the 1960s.

Moreover, federal, state and local officials say that the least expensive and only fail-safe way to protect life and property from flood is to keep development out of the river’s channels and flood plain.

The debate over what to do with the river in the aftermath of the flood, which claimed the life of a homeless man who camped in the river bottom and threatened more than 100 other homeless people and RV park residents, pits a developer and his allies against public works officials, scientists and preservationists.

“The developer who claims the river should be cleared is just trying to cover his own butt,” said Cathy Brown, a U.S. Fish and Wildlife Service biologist. “It’s still a dynamic natural river with tremendous value to the ecosystem and the endangered species that depend on the estuary.”

Strict protection laws, including the federal Clean Water Act and the Endangered Species Act passed during the 1970s, prohibit officials from clearing the river of vegetation if such action would disturb wetlands or the endangered species that thrive in the riverbed and its banks.

State and federal regulators say those consequences are inevitable if vegetation is uprooted.

Also, removing the river’s islands of reeds and willows would be expensive, require extensive federal and state permits, and probably would have to be repeated every year, Ventura County public works officials said.

A better option, officials said, is to let nature do the work for them, cleaning out the channel with a periodic sweep of floodwaters.

Arnold Hubbard, owner of the Ventura Beach RV Resort, acknowledged that there were risks in building where he did, in a portion of the river bottom designated as flood plain.

But Hubbard said he believes that damage to his property could have been avoided if the riverbed had been cleared of brush and trees. The Ventura County Flood Control Department should protect his development against floods just as the Police Department protects it against crime, he said.

“He was warned repeatedly that he was proposing a development in the flood way of a river,” said Brown of the Fish and Wildlife Service.

“He is not entitled to protection,” said Alex Sheydayi, director of Ventura County public works. “We don’t protect people who intentionally build in the river bottom.”

On the morning of Feb. 12, after a week of back-to-back storms that saturated much of the 226-mile watershed of the Ventura River, the riverbed, which is dry most of the year, became a deadly torrent that carried sediment, brush and rocks from its headwaters 16 miles to the sea.

Dolores Taylor, Ventura County hydrologist and engineer, estimated that brush and vegetation, combined with moving sediment and rocks, made up 40% of the river’s bulk. Much of it was carried down from the headwaters of the river, she said.

Taylor said the river did what it was supposed to do in carrying sediment and brush downriver and out to the ocean. But she said some brush got hung up on vegetation on its way. Although no one in Ventura County has advocated that the river be paved, Donald F. Nichols, assistant deputy director of the Los Angeles County Department of Public Works, said the 40-mile concrete channel that is the Los Angeles River performed well during the latest storm.

“The concrete channel allows folks to live near the channel and prevents overflow,” he said. Although biologists cite the Los Angeles River as an environmental disaster and some environmentalists advocate removing the concrete, Nichols said he would ask the Army Corps of Engineers to build it now if it had not been done more than 40 years ago.

Mark Capelli, a biologist and lecturer on coastal processes at UC Santa Barbara and a member of the Friends of the Ventura River, said the events of Feb. 12 should be seen not as a flood control problem but as a historic event.

“We’ve heard lots about wetlands being destroyed,” he said. “But on Feb. 12, we saw Mother Nature making and remaking wetlands and creating a delta. We were witness to a tremendous physical process.”

Key Floods

There have been five major floods of the Ventura River since 1938, their seriousness measured in the amount of cubic feet of water flowing down the flood channel per second or cfs. A cubic foot of water is about 7.5 gallons; a fire hydrant with its valve fully open gushes at the rate of about 1 cubic foot per second. In any given year, there is a 10% chance that a 10-year storm will occur. A 50-year storm is one that has occurred on average once every 50 years, and there is a 2% chance that it will occur in any given year.

YEAR DATE RIVER FLOW KIND OF STORM 1938 March 2 39,200 cfs 10-year event 1969 Jan. 25 58,000 cfs 50-year event 1969 Feb. 25 40,000 cfs 10-year event 1978 Feb. 10 63,000 cfs 50-year event 1992 Feb. 12 58,000 cfs 50-year event

SOURCE: Ventura County Flood Control District