HOLDING L.A. RIVER; SEPULVEDA DAM WATCHED AS WATERS RISE.

Byline: Jesse Hiestand and David R. Baker Daily News Staff Writers

Twice in the last week, police and fire officials nervously watched water climbing behind the Sepulveda Dam and started preparing for the worst - an evacuation of neighborhoods downstream.

Never in the dam's 56-year history has such an evacuation happened.

Backed by a storage basin that doubles as a park, the dam can hold a staggering amount of water - enough to flood 15,813 football fields each a foot deep. No storm yet has been able to top it, although one in 1980 came close.

Still, police and fire officials say they can't ignore the possibility - however remote - of a flood or even a dam breach.

``We would need to see the second coming of Noah,'' said Los Angeles police Lt. Charles Roper with the department's Office of Emergency Operations.

But, he added, ``We have to look at every contingency, no matter how improbable or unlikely they may be.''

When the first El Nino-spawned storm of the season hit last week with fury, police were the first to sound the alarm.

``They said, Listen folks, at the rate the water is coming up we may have to consider evacuation,'' said Ellis M. Stanley, an assistant city administrator with the Division of Emergency Preparedness.

Creating even more urgency was a brief malfunction in one of the dam's gates. To handle the evacuations, officials say they notified the schools, hospitals and the American Red Cross.

``Everybody was alerted, and if it went, we were all set up to go,'' said California Highway Patrol spokesman Dwight P. MacDonald.

In the end, none of the plans had to be carried out, but emergency response officials said the alert allowed them a chance to hone their strategy.

Evacuations

What they feared is that if the dam were to overflow, the Los Angeles River wouldn't be able to contain the flow and waters would inundate neighborhoods in Sherman Oaks and Studio City.

Authorities knew that freeways would have to be closed and residents evacuated. But in the past, few of the details had been decided.

Meeting throughout the day Tuesday, they plugged into this basic plan people, places and agencies, deciding which steps to take first.

With the state's fourth-busiest freeway intersection directly downstream from the dam, the California Highway Patrol would be directed to shut down the Ventura and San Diego freeways, MacDonald said.

The Ventura Freeway would be closed from Woodman Avenue to White Oak Avenue and the San Diego Freeway from Getty Center Drive to Victory Boulevard.

The Los Angeles Police Department would handle the actual evacuations. Some 400 officers would initially go door-to-door to encourage people to leave the area voluntarily, said LAPD Officer Mike Partain.

Those people who were unable to leave on their own would be directed to predesignated sites where they would be taken to shelters by school or city buses.

Those shelters, officials decided, would be at North Hollywood, Grant and Van Nuys high schools and would be run by the Red Cross and Salvation Army.

As for residents who refused to go, ``if the Fire Department incident commander, who we are under the direction of, makes it a mandatory evacuation, you will leave,'' Partain said.

Police would also be responsible for keeping unauthorized people out of the area to prevent looting and maintaining routes through the area for fire and ambulance crews.

They have even worked out tactics for the worst case, a catastrophic breach of the dam. North of the Hollywood Freeway along the Los Angeles River, water could be 10 feet to 19 feet high, with the torrent moving at from 5 feet per second to 12 feet per second.

A distant possibility

The circumstances needed to create a rupture or even floods below the dam, disaster planners say, fall squarely under acts of God.

The dam, which lies within seven miles of two earthquake fault systems, can withstand a 6.7-magnitude temblor, according to the Army Corps of Engineers, which built and operates the dam.

For water to climb anywhere near the top of the spillway takes serious, steady rain: about 9 inches in 24 hours.

Even then, the dam would not overflow easily. As the water rises, it spreads out, flooding the golf course, baseball diamonds and bike trails behind the dam. An ever-greater amount of rain, therefore, is needed to make the water rise those last few feet to the top of the spillway, 700 feet above sea level.

Raising the spillway gates gives another 10 feet of protection before the water overflows. Few storms can dump that much rain, Roper said.

Still, with 152 square miles of city and mountains draining into the Sepulveda Basin, some storms have come close. A storm in 1980 set the record height at 705.1 feet, halfway up the spillway gates.

Wild-card storms

As torrential rains battered the San Fernando Valley last week, police and fire officials had no way of knowing exactly whether the storm would peter out, pick up strength or stall over the dam. In February 1992, what was supposed to be a minor storm unexpectedly stalled over the Valley and trapped 48 people in the flooded basin as water behind the dam climbed to 702.69 feet.

With this in mind, police watched last Tuesday as water in the basin continued to rise fast - and rain was expected to continue throughout the day.

``We said, Let's look at what we're going to do in case the back end of this storm is as strong as the front end,'' said Sgt. Ron Spicer.

Officials activated the emergency operations center at Los Angeles City Hall, where representatives of 30 agencies gathered to coordinate their efforts as rain-related problems cropped up across the city.

Out in Van Nuys, fire officials set up a command post at Station 88 on Sepulveda Boulevard, just across the San Diego Freeway from the dam. From there, firefighters kept an eye on the rising water.

Broken gates

These concerns were heightened when one of the dam's gates malfunctioned, said Assistant Fire Chief William B. Ward of the Los Angeles City Fire Department. These gates are designed to control the flow of water from behind the dam; too little and the dam overflows, but too much, and it could cause the Los Angeles River to overflow its banks.

``It moved our whole process up much sooner,'' he said.

An Army Corps of Engineers spokesman said the problem was a simple mechanical malfunction, quickly repaired, and posed no serious threat.

Still, officials were taking no chances. They dusted off longstanding plans for handling everything from minor dam overflows to a catastrophic rupture.

Although those who participated in the meetings, as well as members of the Army Corps of Engineers, insist that kind of disaster is unlikely, they differ on just how unlikely.

According to the Army, even if water spills over the top of the dam, the river channel below should be able to accommodate the extra flow without flooding.

Police, however, say that in some emergencies a spill could overload the channel below, threatening surrounding neighborhoods.

``Any time you have a release past a certain amount, the riverbanks can't hold it,'' said LAPD Capt. Sandy Watson.

Although Angelenos tend to worry more about earthquakes than floods, Bob Canfield, one of the city's top disaster planners, cautioned against downplaying the lethal power of an urban deluge.

``In the '69 floods, we lost about 100 people,'' he said. ``I don't underestimate the danger of a flood, and you have to be alert to that danger.''

Daily News Staff Writer Rick Orlov contributed to this report.

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