San Diego — The Lariat is on the verge of sliding. You can feel it. Celso Rodríguez grinds to a halt. He gingerly eases the Ford truck back down the hill. At the bottom he gets out and leans over his left front wheel. Then he walks around to the right front wheel. He's adjusting the knobs on the axle. He gets back in. "Now we're four-by-four," he says. "That should do it." He starts the truck, whining and slicking, up the mud track again.

The road is Calle Adolfo Ruiz Cortinez, in the hills between Tijuana and the coast; we're looking for Dorotea Garay's house. After recent heavy rains, she's afraid her house is going to tumble down the hill into the canyon below. We bump up the unpaved calle and squish to a stop beside a young man digging mud out from the bulging side of the road.

Over the edge, the cliff drops nearly straight down into a canyon dotted with small houses. Rooster crowings and dogs' barking echo up to us. The tarpaper roof of one tiny house juts out below the level of the road. Dorotea's son, Eduardo, 23, puts down his shovel and comes over. "Your house is sliding?" asks Rodríguez. "Something started moving last night, after the rains came," answers Garay. "It frightened my mother."

Rodríguez leads us down tiny round steps made of mud-filled tires, to the little house. He has a clipboard and pen in his left hand. Protección Civil (Civil Protection), read the three-inch-high yellow letters across his blue jacket. He's doing his rounds, responding to worried, sometimes desperate pay-phone calls from those living in the poorest hilltop colonias.

Garay's two-room box-house tucks in against an eight-foot dirt wall, dug into the hillside. Right now, the wall is soaked; the doorframe, leaning sideways, speaks to the home's lack of stability. The door won't close anymore. The mud from the road threatens to cave in on this house, which threatens to collapse onto a lower one. Ice plant and a carpet thrown over the cliff haven't stopped the mud-fall oozing down two levels.

Dorotea Garay appears above. She throws her hands up, then hurries down the tire-steps. She's about 40, wiry, a single mom originally from the state of Nayarit. She works far away in Otay at a maquiladora called "Kendall," according to the I.D. card she shows Rodríguez. She makes bolsas para enfermos -- medical bags -- for 520 pesos a week, about $55.

"Last night in the rain," she says, "it could have been because of these pills I take, but when I put my hand against the wall, it moved. What can we do?"

"This land is in a very high-risk zone," says Rodríguez. "The water is soaking in and weakening the earth. It's not going to hold on. A little more rain and your house might slide down." Rodríguez says he needs to see her papers, to check if she is here legally. We ease past two 44-gallon plastic water barrels, a new plastic-pipe faucet nailed to the plywood wall, and a five-foot gas cylinder connected to a gas stove inside. Four bunks fill up the rest of the room. Dorotea and Eduardo haul out a suitcase from under one of the bunks and start hunting for papers. The little room has two photos of children, a cluster of gilted soccer trophies Eduardo has won, and a soccer pennant. A total of three adults and seven children live here and in the hut below.

Outside, four toothbrushes and an open tube of toothpaste peek out from a cement basin.

"In the 1993 floods I covered the roof with a tarpaulin," Dorotea says to Rodríguez, who is examining her papers, "but this time, I don't have any money."

"If this house falls, it's going to land on the other one," says Rodríguez. "Or maybe part of the hill will come on top of you. Please take precautions and look for another option. Especially if it starts raining again. And we are expecting rain."

Rodríguez starts talking to Garay about moving; about contacting CORETTE (Comisión Reguladora de la Tenencia de la Tierra del Estado), the state commission that regulates cheap, undeveloped land to the poor. "Have any of your neighbors fixed their papers with CORETTE?" he asks. Garay doesn't know. "Well, in the meantime, ma'am, if the rain comes again, please look for a more secure place. Perhaps with family. This is my recommendation."

* * *

For Rodríguez's boss, Antonio Rosquillas, Tijuana's civil protection chief, the rains that hit San Diego and Tijuana last week have marked an anniversary. It's 20 years ago this month since Tijuana experienced its worst floods since the "100-year" flood of 1916. "I remember the floods of 1980 very clearly," Rosquillas says, in the operations room of his pink-marble-tiled headquarters downtown. "I had joined the volunteer Halcón ("Falcon") rescue group six months before. The floods struck January 30. I had just turned 19."

The day Rosquillas's group was called out to help, the Tijuana River burst its banks after heavy rains and a sudden release of water from the Rodríguez Dam. It swept away entire riverside neighborhoods. Official death figures were 20. "But the word on the street was that more than 200 people died," says Rosquillas. "Our group was driving through the little streets down on the river. People would say, 'I don't want to leave my home. It's another trick of the government.' The government was trying to take their land for the canalization of the river. So we just had to say, 'Okay, okay, bye. We've got to go,' because the water was rising. We had a four-by-four truck, trying to escape. The water rose very, very fast.

"I saw nine members of a family on the roof of their house about 100 yards from the river shore. The house was in the middle of the current, and we had no equipment to make the rescue. And after 20 minutes, we saw the house disappear in the river, along with the family members."

Thirteen years later, Rosquillas was visiting a friend in local government on his day off. It was January 6, 1993, his 32nd birthday, and this time, the start of the worst floods of the '90s. At least 33 people died. "At the time, I was helping my sister run her restaurant in Chula Vista. But then the rains started, I volunteered, and a week later they asked me to accept a job with the local Civil Protection." That's when Civil Protection began in Tijuana. In the seven years since he has become its director, Rosquillas has fought to get basic equipment like computers, two-way radios, multiple phone lines, and meteorological-monitoring stations. "Even though we now have more [emergency] equipment in Tijuana than any city in Mexico [apart from Mexico City], our annual budget [$400,000] compared with San Diego's is very modest."

Rosquillas says he watched San Diego's Channel 10 news last week and couldn't help smiling at the contrast in scale. In San Diego, well-equipped organizations deal with rain-caused problems such as swollen streams and sagging walls.

"Here in Tijuana we have a small organization and big problems, such as no pavement on the streets of many colonias, no water, no sewage...we don't have storm-drains. Land use hasn't been [worked out]. We have industry and homes side by side. People here in Tijuana make their homes on the hills. That's a risk for a start. In San Diego they have very good control of all settlements and development. They have very good planning. We don't. Civil Protection has to take care of storm drains, we have to check construction [of new buildings, to check they are built according to code]. We have to coordinate the different agencies, we have to coordinate rescues."

And yet, San Diego's office of Emergency Management is only 3 people, far fewer than Tijuana's 15-strong organization. "Why?" says Rosquillas. "Because San Diego's water authority, public works office, firefighters, police, city, all have their own offices for emergency provisions. So they do all the work in each office. In Mexico we don't have that culture.

"Here in Tijuana I see meetings, urban-planning symposiums, but I never see any topic on disaster-prevention. The architects, the people in charge of planning, they never talk about the possibility of disaster in the city. In Japan, in the U.S., England, Germany, France, they talk about the need for a safe city. They started working that way in Mexico City after their [1985] earthquake. But that attitude isn't yet here in Tijuana. They don't invite me to development meetings. They think that Civil Protection is something to confront an emergency, not to prevent it. It's not the mayor; he's great. It's the system. We have to break the inertia.

"Right now I'm talking to different government department directors, and I'm asking them, 'Hey, let me be a part of the planning to [help] make the rules. But if I am only going to be responsible just to attend to the emergency when it happens, you have to be responsible for preventing the emergency in the first place.' "

Chris Bach, San Diego's Civil Defense Emergency Management coordinator, admits his organization is much bigger, better equipped, better funded, and part of a pervading "prevention mentality" in city hall. "San Diego is a very large jurisdiction, and the fact is we can bring resources to bear, and when we get involved in something, a lot of times we throw the world at it." In the 1993 floods they sent 38 bulldozers and other heavy equipment to Tijuana to help the city shore up against floodwaters. "We don't come up short in those instances." He says he has a high respect for Rosquillas and his organization. "They have a lot of expertise down there. There are a lot of professionals working in Antonio's organization."

But when it comes to working together, Bach says a 1996 bomb incident at Tijuana's Rodríguez Dam illustrates the problems. "In the past, one of the problems we've encountered is that some of the decisions that impact the local Tijuana jurisdiction are made in Mexico City. It slows down the process. In this instance there was a suspicious package reported on the face of the dam. It was reported as an act of terrorism, and there was supposedly a bomb there. And the federales came in and closed the whole thing off. The locals weren't even in the loop on what was going on. And the decisions that were made to mitigate that problem were all being made in Mexico City." According to then-city manager Jack McGrory, "It took [Mexico] eight or nine hours to notify us."

San Diego authorities had legitimate cause to be concerned. "If Rodríguez Dam were to be blown [up], [the resulting flooding in Imperial Beach] would exceed the 100-year flood we had in 1916," Carolyn Powers of the Tia Juana River Valley County Water District told reporters in March 1996. In the 1916 flood, she said, sections of Imperial Beach and Palm Avenue were under eight feet of water.

"One thing is sure," Bach says. "If [a similar incident] ever happened in the city of San Diego, we would not turn it over [to federal authorities]. It would be ours."

"The Rodríguez Dam is one of the most dangerous dams in Mexico," acknowledges Rosquillas, "because of the high concentration of population downstream. If the Rodríguez Dam is full, and we have an earthquake, and the dam fails, if it breaks completely, it will be a total disaster. Although, if they have to open the gates, the channel was constructed to receive the water from seven open gates in the dam." But, he says, Tijuanans also have to keep a wary eye on U.S. dams. "You have Morena Reservoir and Barrett Lake [in San Diego County]. If earthquakes ruptured their dams, those waters [would smash through] Tijuana before they return to the United States in San Ysidro."

* * *

Celso Rodríguez points the Lariat up Quick-Death Canyon (Cañón del Matadero). We bounce past a basketball court on the verge of collapse. Raging floodwaters have eaten out the rubble beneath one whole corner. A hilltop house exposes its foundations where the land has fallen away. This time we're responding to a colonia shop-owner's plea. A wall of mud is shunting her entire shop forward. Just before tackling the steep boulder-strewn slope, Rodríguez stops to engage the four-wheel-drive again. You suddenly get a view through the hills to San Diego, the Coronado Shores condos, Point Loma. It looks like a pastel painting, a dreamland. But Rodríguez is too busy to notice.

As of Tuesday, Dorotea Garay's house was still standing, but Rosquillas expects more storms this weekend.