Plan to Level Levee Alarms Residents

A developer is preparing to tear down a Depression-era earthen embankment, near the mouth of a Rancho Cucamonga canyon, that many experts say provides indispensable protection for hundreds of homes, several schools and the nearby Ontario International Airport.

Part of the 1.3-mile-long levee could come down any day.

The decision to remove it is based on the U.S. Army Corps of Engineers’ widely disputed contention that a dam and debris basin built in 1983 can stop the torrent of mud and rock that could spew out of the San Gabriel Mountains in the event of a major flood.

Prominent among the corps’ dissenters is one of its own, Robert Kirby, a former hydrological engineer who helped design the structure. Kirby has signed an affidavit saying he is concerned about homes, businesses and schools because he fears the Deer Creek Debris Basin has only about 40% of the flood-control capacity it was designed for.

“I strongly believe that it would be irresponsible to remove the levee until the lack of capacity of the debris basin has been corrected,” Kirby wrote after inspecting the dam last year.

Kirby is not alone. A California Department of Water Resources task force, two consultants hired by homeowners and Ontario airport officials have all expressed doubts about the debris basin--a stadium-like structure formed by the 57-foot-high dam at the mouth of the canyon.

The corps built the dam above the levee and turned it over to San Bernardino County.

Several hundred people live just below the levee; several thousand live in the flood plain. The levee’s removal is part of a plan, approved by city and San Bernardino County officials, to build 40 more homes, some of them within half a mile of the dam. The airport is seven miles south of the dam.

The state Department of Education has halted funding for the construction of a high school in the flood plain. And both U.S. Sens. Barbara Boxer and Dianne Feinstein have urged the corps to reevaluate the plan, saying it might pose a threat to public safety.

“I don’t care if they build houses up here,” said William Hawkins, a general contractor and neighborhood resident. “The biggest problem is that the city, the county and the federal government have ignored a very basic safety issue that could affect thousands of people.”

Corps officials concede the project could not hold back the amount of flood debris for which it was designed, but they say it meets federal criteria for flood safety and can contain the amount of water generated by a so-called 100-year flood. That is a flood with a 1% chance of occurring in any given year.

“We have not changed our position that the Deer Creek project provides a good level of protection,” said Joseph Evelyn, chief of the hydrology and hydraulics branch of the corps’ Los Angeles district. “Given the uncertainty involved in this kind of work, anyone looking at the situation can always come up with a different opinion.”

The uncertainty is heightened in the San Gabriel Mountains, where heavy storms can combine with fire damage to create a destructive slurry of boulders, gravel and sand. Unlike with more conventional floods, there is no federal standard for containing such debris flows.

According to the corps’ own data, the Deer Creek Debris Basin can hold 162 acre-feet of debris, whereas the centennial event is likely to let loose 292 acre-feet of material, corps officials say. One consultant retained by homeowners concluded that the basin could hold only 112 acre-feet of debris.

What would happen during that scenario has been the subject of rancorous debate for several years. The corps says an existing spillway and flood channel would accommodate debris that the basin couldn’t hold. Nearby Rancho Cucamonga residents say they would be in the path of a deluge.

Bob Cristiano, the Newport Beach developer who wants to remove the levee and build homes, blames local residents for whipping up a hysteria that no politician could ignore. “I think the tragedy here is that these homeowners will end up making thousands of people have to pay for flood insurance,” Cristiano said. “This is principle; I’m not going to lose the right to build on my land because someone has the audacity to lie.”

Cristiano is grading his property to build 40 houses just below the dam, high on an alluvial fan, with horse trails and sweeping views of the San Bernardino Valley. The levee runs south from the foot of the mountains through Cristiano’s property and east to a flood channel. To the north, the mountains loom at strikingly steep angles, rising to nearly 9,000 feet at Cucamonga Peak.

The developer has been trying to build on his lots for years, but has been thwarted by more than a dozen legal challenges, mostly based on environmental grounds, to block it. He has won every one.

“This is ‘NIMBY-ville’ here,” Cristiano said, in reference to a Not-In-My-Backyard attitude. “You have some very spoiled, rich people who have lots of money and no brains.”

Corps’ Explanation Is Called Orwellian

Residents say they are trying to protect themselves against a catastrophe.

Malissa McKeith, a resident and environmental attorney who is leading the fight, says the corps’ distinction between a 100-year flood and a 100-year debris flow is Orwellian. “What is the difference when it comes roaring through our neighborhood?” she said.

“I’ve spent $80,000 on [a consultant],” McKeith added. “I’ve spent all my retirement [savings]. I’ve mortgaged my house. It is not about that levee or 40 homes. It is about the corps building things too small and fighting people who simply want a study.”

She wants the federal government to conduct a review of the dam in light of the conflicting opinions about its safety.

McKeith has acquired old inundation maps that show how the levee diverted flood debris that might have plowed into houses, had any existed, during heavy flooding in 1969.

To underscore the danger of debris flows, she shows photographs of Volkswagen-sized boulders that rolled out of the mountains during a flood.

A study McKeith commissioned by Exponent Failure Analysis Associates concluded last year that the basin holds 112 acre-feet of debris and could contain only a 20-year event--one that is much smaller and five times more likely to occur in any year than a 100-year event.

“If the 100-year event occurs, the basin would fill up, and debris would flow down the spillway into the flood-control channel,” consultant Douglas Hamilton concluded. “The size of debris and the speed of its movement down the spillway [are] likely to disintegrate the concrete channel bed and walls and spread back out, causing flood waters to escape the channel in a manner similar to that before the flood-control project was built.”

The vulnerable area includes a number of new schools and new housing developments, as well as the Ontario airport, Chaffey College and the Milliken Landfill.

Hamilton asked a recognized expert in the field, Michael Bohlander, the head of the Hydrologic Engineering Section of the Los Angeles County Department of Public Works, to review his findings.

Bohlander agreed with Hamilton’s calculations on the capacity of the basin and concluded a letter to him with a warning about similar situations in L.A. County: “We experienced some overflows of debris basins that plugged the downstream channels and storm drains. This in turn allowed general widespread flooding.”

After McKeith showed them the Exponent report, officials at Los Angeles World Airports, which runs Ontario airport, hired their own consultant, John J. Cassidy. His assessment of the basin’s capabilities was even more pessimistic.

Cassidy said that the debris basin would hold less than 100 acre-feet. Moreover, he said, the channel that flows out of the basin could not handle the amount of flood water generated by a 100-year-flood. Cassidy and several other experts said such a flood could produce three times more runoff than the corps’ estimates for such an event.

Following Cassidy’s report, the executive director of L.A. World Airports wrote Sen. Feinstein, urging her to recommend a $1-million appropriation to study the flood-control structure.

“There’s enough conflicting information out there that we want the federal government to conduct a study to demonstrate that we have the protection that we believed we had,” said Deputy Executive Director Roger Johnson.

In response to requests by Boxer and Feinstein, the state Department of Water Resources convened a task force in January to make recommendations on Deer Creek. The task force has not completed its investigation but reached a tentative conclusion that the basin could not handle a 100-year event.

The controversy is complicated, however, by official disagreements over the rate of flow generated by a huge flood.

After the 1969 flooding, the U.S. Geological Survey data showed that about 7,000 cubic feet per second of water probably rushed into the basin. The channel built in the 1980s can handle 5,400 cubic feet per second. The USGS now says its data were flawed, although John Singer, a former USGS hydrologist who collected some of the stream data during the 1969 event, insists that the original data are accurate.

The Army Corps of Engineers says the 100-year flood would produce a water flow of only 2,700 cubic feet per second.

All parties concede that the science of debris flows is far from exact. Evelyn of the corps said the dam’s critics--namely the consultants and the former hydrologist who helped design it--are credible experts in the field with simple differences of opinion.

He said that even if the debris basin is not designed to handle a 100-year debris flow, it does not mean it can’t handle the fallout. Some of the debris would flow into the outflow channel, Evelyn said, and some would continue to mount behind the earthen dam, backing up into the canyon.

“Just because we don’t have the storage capacity of the debris in a 100-year event doesn’t mean that San Bernardino [County] will have flood damage,” he said.

Ken Miler, the director of the county Department of Public Works, which operates and maintains the debris basin, said he trusts the corps’ expertise but will heed the state task force if it ultimately concludes that the structure is dangerously undersized. Miller said remedies could include excavating a bigger debris basin, making the dam larger and building other levees below the dam.

“We want to make sure it’s safe,” Miller said. “We’re not just going to stand on our opinion and say it’s safe, to heck with other opinions.”