Armando Reyes climbed over the border fence and prepared for the dash into San Diego. But his smuggler instead led him and four other migrants through a patch of reeds to a stinky drainage pipe, and ordered them inside.
The black sludge reached Reyes' chin as he crawled through the shoulder-width tube. Rats scurried by. Terrified of losing his way in the darkness, Reyes reached for the illegal immigrant in front of him and clutched his sneaker.
The stocky 28-year-old from Oaxaca had followed the smuggler into a vast labyrinth of drainage pipes under Otay Mesa, a booming commercial area of San Diego 15 miles southeast of downtown.
The 23-mile network leads to about 500 manholes scattered across about three square miles. From those openings into the bowels of the city, mud-covered migrants crawl out into streets, busy intersections and parking lots, creating a dizzying guessing game for U.S. Border Patrol agents.
"They're popping up all over the place," said Joe Perez, the agent in charge of the area.
The migrant traffic below truck-clogged streets and new office parks underscores the persistence and desperation of people faced with crossing one of the most heavily fortified sections of the border.
Illegal crossings will soon get even tougher. President Bush is sending 6,000 National Guard troops to the border, Congress is mulling its own enforcement plans and starting next month this busy frontier across from Tijuana will be monitored by remote surveillance cameras.
So the underground beckons.
The tunnels channel rainwater out of flood-prone areas, but when the waters aren't running, the waves of migrants flow, a phenomenon that has bedeviled agents for years and has gotten worse recently as aboveground routes have become more heavily patrolled.
The cat-and-mouse game took an ironic turn last month when migrants even surfaced outside the offices of the U.S. Border Tunnel Task Force. Those manhole covers -- one in a secured parking lot -- were welded shut after that, one of them also topped with three 35-pound bags of rocks and gravel.
But six more manholes, all potential escape hatches, lie within a block of the federal facility.
"They're all interlinked, so you never know where they'll come up," said David Badger, a Border Patrol supervisor.
Other border cities have wrestled with similar situations, most notably Nogales, Ariz., which is linked underground to Nogales, Mexico, by two large storm-drain tunnels patrolled regularly by heavily armed agents.
Unlike Nogales, the drainage system under Otay Mesa doesn't extend into Mexico. But most of the tunnel outlets are just a quick run from the border. Illegal immigrants typically traverse the pipes, many of which are 2 to 3 feet in diameter, at night, sometimes crawling for hours. Vehicles waiting on deserted streets then whisk them to stash houses.
Border Patrol agents have arrested hundreds of migrants exiting storm drains in the last year but don't know how many get through. Some estimate that thousands make it.
Last year, a Caltrans worker said he saw 200 migrants climb out of a manhole in the middle of an interchange on State Highway 905. Last month, 17 people were captured after they climbed out of a manhole near the Drug Enforcement Administration building that houses the tunnel task force. And earlier this month, 15 people were arrested outside a warehouse just north of the border after an agent heard the scraping sound of a manhole cover being slid open.
The problem has grown serious enough that agents are teaming with San Diego city engineers to create a computer map of the system. Research is also underway to find a way to attach sensors to manhole covers to alert agents when they are opened. Crews have welded shut about a dozen manhole covers known to be active migrant funnels.
At the tunnel task force, the federal multi-agency group credited with the discovery in January of the longest illegal border tunnel ever found, a top official said the storm drains present a unique problem.
"It's not like when you have ... a drug tunnel. We can't go in there and just fill them up with cement," said Michael Unzueta, the special agent in charge of Immigration and Customs Enforcement.
The federal task force focuses on unearthing drug tunnels built by organized-crime groups. Policing the city's storm drain system is the responsibility of the Border Patrol.
Migrant smugglers possess extensive knowledge of the storm drain system, agents say. The smugglers are typically young men from Tijuana, sometimes teenagers, who wear black jumpsuits and kneepads and mark their subterranean routes with construction tape or paint. The smugglers have been known to ferry drugs through the tubes, but most of the smuggling appears to involve people.
They often deceive the migrants, telling them the underground trips will take only minutes. Those who fall behind are often berated and ordered to hurry up. Some have even gotten stuck inside.
Illegal immigrants, who pay from $1,500 to $3,000, often don't know they are going underground until smugglers give them Styrofoam kneepads and tell them to get into the pipes.
Reyes, who was headed for Los Angeles, said his smuggler told him the crawl would take just five minutes, but half an hour later he was still inching along. It was cold and so dark, he said, that he couldn't see his hand in front of his face.
"I didn't want to get lost.... I just wanted to get out of there," he said.
When he finally surfaced, agents, who had been watching the manhole in a warehouse district a quarter-mile north of the border, pounced and arrested him and 10 other people. At the processing center in Chula Vista, agents hosed off the migrants, who were covered in muck from head to toe.
"It's frightening.... My nerves are shot," said Reyes, shivering in his wet clothing. "I'll never go down there again."
The pitch-black passages are harrowing even for veteran city workers.
"It's kind of scary," said Aaron Snelling, a drain supervisor with the city of San Diego. "It takes a while to get used to. You get down there, get your work done and get out."
Smugglers think of crafty ways to clean the migrants quickly. A getaway truck found last year when agents busted 52 people near a manhole was equipped with a hose, showerhead and water tank so the migrants could wash off.
Tips about active manholes come from startled motorists, Caltrans work crews and security guards; otherwise, most cases require patient detective work and a good eye for subtle details.
Agents pinpoint active manholes by looking for muddy footprints. The 90-pound covers sometimes leave scrape marks on sidewalks or are left slightly ajar. And discarded clothing is usually a sign of activity because migrants frequently change after leaving the tunnels.
Looking down into one manhole on the edge of a field where pants and shirts had been found, Perez could only guess what had transpired the previous night.
"It's the unknown. We have no idea what came through here," he said, adding, "I wouldn't be surprised if they ran 75 to 80 bodies through."
The Border Patrol has yet to find a sure-fire method of keeping smugglers and migrants out of the drainage tunnels. Many agents don't enter the pipes for safety reasons: Dangerous chemicals can flow in the runoff waters. Sealing all of the manholes is not an option because city workers need access to maintain the system.
Agents have installed heavy grates over the 11 openings near the rusty border fence, but smugglers regularly cut through the bars with blowtorches and saws. There have also been several attempts by smugglers to build tunnels that link to the drainage system.
Perez, who has spent decades in the area, remembers when migrants streamed into California here across open farmland.
The landscape has changed dramatically: Double fencing and stadium lighting line the border; warehouses and office parks have grown up on the vacant land.
And the migrants keep coming.
"They don't have to cross fields," Perez said. "They went underground."
Times staff writer H.G. Reza contributed to this report.