The term "crisis on the border" typically refers to immigration issues or drugs being smuggled into the country. But it has one more meaning, as we discovered, when we went to the border in early February: tens of millions of gallons of raw sewage that spill every year into the Tijuana River on the Mexican side and flow across the border right into Southern California, polluting the land, air, and sea.
Mexico and the United States each thinks the other should be doing more to clean it up, with no effective solution found on either side of the border for decades.
This is where the Tijuana River crosses the border into the United States. This cement structure was built to contain flooding from rainfall. But this isn't just rain water, it's a toxic mix of raw sewage from neighboring Tijuana, draining into Southern California on lower ground, eventually emptying into the pacific ocean.
Amber Craig: So, it effectively-- it's like a toilet flushing straight into this river valley.
Border Patrol agent Amber Craig took us on a tour of the sewage infiltration, showing us that what doesn't flush out to sea, washes up on land. Mountains of plastic bottles, furniture and tires.
Amber Craig: And this is a concern for us, too, not just because it's debris and waste, but because the mosquitoes love to nest in it, so...
It's a health concern, an eyesore, and it's hindering the Border Patrol's main mission. She took us to see President Trump's newly erected wall along the border: just this six-mile stretch cost an estimated $50 million.
What we found is that under the wall, there's a network of basins and tunnels built 30 years ago to try to capture the sewage from Tijuana. The red dot is me, next to agent Amber Craig, inside one of those concrete sewage collection basins. It's connected on either end to tunnels from Mexico to California that were constructed right under the wall.
Lesley Stahl: So you think of the smugglers and the migrants building tunnels to go under the wall. But the U.S. government built this tunnel that goes under the wall.
Amber Craig: Yes, we built this so that the water would flow freely into the United States.
It has to flow freely because four decades ago the U.S. signed an agreement with Mexico not to cause backup flooding at this area of the border. These metal grates at the ends of the tunnel let the water in while keeping the rubbish out. It typically works fine during dry weather, but not when it storms.
Amber Craig: The amount of water that comes through here comes through like a torrent. It is very, very dangerous. It is a raging river when it rains.
Lesley Stahl: With the tires and the barrels and everything--
Amber Craig: Full of debris and garbage. That's correct. It's very dangerous.
The debris and garbage can hurtle down here with such force that Border Patrol agents have to open the grates to prevent the system from clogging. That means trash flows into California unobstructed. It's also an opening for migrants.
Lesley Stahl: The purpose of the wall is being totally defeated by this obligation of yours to lift the grates.
Amber Craig: You-- well, yup. It does make it a little more challenging to have to have that open. Of course, we don't want to have it open.
Lesley Stahl: If they go through that tunnel, they're in the United States.
Amber Craig: If the grates have to be opened, then we have to have a personnel, an agent, on the other side, keeping--
Lesley Stahl: So as they come out.
Amber Craig: That's correct.
Lesley Stahl: How do the smugglers know that the grates are lifted?
Amber Craig: They watch.
Lesley Stahl: They watch?
Amber Craig: Sure. There're smugglers watching us probably right now.
Migrants are routinely caught risking their lives crossing in the sewage: some need to be rescued and decontaminated.
Lesley Stahl: Let me read you a list that we found of stuff that is in this water: fecal coliforms, drug-resistant bacteria, benzene, cadmium, mercury, hexavalent chromium medical waste, and DDT, which has been banned for years in the United States.
Amber Craig: Yes, ma'am.
Lesley Stahl: I hear that sometimes the water turns funny colors?
Amber Craig: It does. We've had bright, bright purple, a bright pink, neon green, dark black.
Lesley Stahl: So the migrants are going into this?
Amber Craig: Yes, ma'am.
Lesley Stahl: And the patrol agents are going into this. Are they getting sick?
Amber Craig: Agents have reported various health injuries. Rashes are very common. Stomach issues. We've had one agent who had a flesh-eating bacteria. And he almost lost his arm.
Lesley Stahl: How angry are you and the other agents?
Amber Craig: We're frustrated, very frustrated. Agents know our job is dangerous. We've signed up for a job where we could be shot at, where we could die in a car accident. And we accept that. Nobody thought that they were gonna come here and be exposed to this, to the sewage, and the chemicals and the smell.
Congress just allocated $300 million to address the sewage issue all along the border, a fraction of what's needed. Especially here, because of the rapidly growing population of Tijuana.
Amber Craig: It is a difficult situation. We're having to deal with another country. And the City of Tijuana, it's just a huge city, it's overpopulated. Their infrastructure isn't-- isn't prepared to handle this kind of flow. So it just comes right over the border.
The local Mexican sewage authority invited us to one of the main treatment pumps in Tijuana. It often breaks down due to mechanical failures. So workers have to wade underground in black sludge to repair the buckling facility. While we were there, one worker got so overwhelmed by toxic fumes he required medical attention.
According to the Mexican authority, the last line of defense keeping the sewage out of the U.S. here is a small crew of sanitation workers who unclog drains by hand along the border. We found one of them, a man named Abel, clearing trash with a rake.
Some of the wastewater that does get collected is pumped into these giant pools six miles south of the border, where the sewage is supposed to be treated and discharged through this massive pipe as clean water into the ocean. But the facility hasn't worked for years, so what you're looking at is untreated sewage emptying directly into the Pacific.
We stood by the torrent with Fay Crevoshay, an environmentalist with Wild Coast, a watchdog group of concerned citizens from both sides of the border.
Lesley Stahl: How much sewage are we talking about?
Fay Crevoshay: Yeah. The local authorities say that it's 25 million gallons a day. We think it's 40 million gallons.
Lesley Stahl: And it's just gushing, gushing, gushing out.
Fay Crevoshay: That's what we have here.
Making matters worse, entire shantytowns have popped up in Tijuana's canyons along the border. Many of these makeshift shacks were thrown-up by people who moved here for jobs, at factories created by the North American Free Trade Agreement.
Lesley Stahl: These factories are dumping their chemicals?
Fay Crevoshay: Sure. We have laws, but there is no--
Lesley Stahl: Enforcement--
Fay Crevoshay: --control. So why spend money? The problem is these factories come here because it's cheap. They're gonna pay the workers $8 a day. And this is the result. This is where the workers live. These houses have no services, no electricity--
Lesley Stahl: No plumbing.
Fay Crevoshay: --no plumbing, nothing.
Lesley Stahl: This stream, this entire stream, is just raw sewage.
Fay Crevoshay: Sewage.
Lesley Stahl: When it rains, what happens to this stream?
Fay Crevoshay: It grows. They have a whole river! You see all the lying garbage, all around it?
Lesley Stahl: Yeah. That--
Fay Crevoshay: It takes it with!
We saw tires everywhere, a lot of them from California that were sold to Mexican car-owners second-hand. When the tires wear out, many are used to prop up homes on the hillside or just get dumped and then get swept by the sewage right back to Southern California.
We wondered where all the untreated sewage that emptied into the ocean goes. Well, we learned that it can flow right by a U.S. military training base. Hard to believe but the Navy SEALs are training right in the path of the sludge.
Lesley Stahl: Let me ask the SEALs, how many of you-- have gone swimming in that?
ALL: All of us.
Retired naval officer Mark West and four retired SEALs - Alex Lopez, Kyle Buckett, Bill Lyman, and Steve Viola - told us how the sewage impacts those training here.
Steve Viola: It wreaks havoc on your system. Stomach aches, throwing up, I mean, coming out both ends—fever. And you just have to suck it up and keep going.
Kyle Buckett: We've had classes of, you know, 38 to 42 guys contract it during their training cycle. And it's a very, it's a big challenge for us to deal with that.
Alex Lopez: I contracted cellulitis. Which is--
Lesley Stahl: What's that?
Alex Lopez: --a bacterial, like, staph infection. It just took off, and it started eating, you know, flesh on both my legs.
They say that the most vulnerable are SEAL BUD/S, those trying out to be SEALs, especially during "Hell Week" –
five and a half days immersed in the ocean, testing their endurance.
Lesley Stahl: Have you heard that during Hell Week the BUD/S now take prophylactic antibiotics?
Steve Viola: Yes, I have heard that.
Lesley Stahl: You were a trainer. Do you ever say, "These kids can't go in this today. I can smell it, I can see it."
Kyle Buckett: Yeah, absolutely. Yeah, we have.
Lesley Stahl: You do-- you do.
Kyle Buckett: We have, we have. And then we have to transition to the bay or to a pool.
Bill Lyman: There's no waves in the bay and there's no waves in the pool.
Lesley Stahl: Are you seeing any reason for us to worry about your readiness?
Mark West: I think, I think that our readiness is being impacted. And you know--
Lesley Stahl: It is being im--
Mark West: Yeah, it is.
The SEALs say the Navy, aware of the sewage issue, is monitoring the water quality. So we found it odd that it is spending a billion dollars to expand the SEALs' training base much closer to the source of the pollution.
Steve Viola: Well we had outgrown the capacity of the buildings that we had. So that's why we moved down there.
Lesley Stahl: But were they taking the pollution into account?
Bill Lyman: No
Lesley Stahl: The Navy did do an environmental impact study.
Kyle Buckett: The Navy's main focus was to see how much we were gonna impact the environment. It wasn't focused on what the environment was gonna impact on the Navy SEAL community.
The Navy turned down our request for an interview, but recently told Congress in a report that the run-off is a concern, yet its impact has been "infrequent and short term," concluding that it is easily mitigated. Serge Dedina, mayor of Imperial Beach, the city on the south-edge of the new base, doesn't buy it.
Serge Dedina: They've ignored the health and safety of their own national security staff, and that's absolutely unacceptable.
Lesley Stahl: Did you ever get any health problems from the water?
Serge Dedina: Yeah. I have a tube in my ear 'cause I had so many ear infections. My kids have gotten sick. Our lifeguards have gotten sick. Pretty much every one of our councilmembers have gotten sick. So it's-- it's devastated our city.
In more ways than one. Imperial Beach is a surfing town, but its beaches are closed a third of the year or more due to the toxic sludge.
Serge Dedina: I've got to spend my time hammering people in power to make sure they understand that dumping toxic waste on Navy SEALs and Border Patrol agents is a bad idea, and getting them to acknowledge that it's actually happening.
Lesley Stahl: If the Navy weighed in do you think things would begin to happen?
Serge Dedina: I think if the Navy brass weighed in, this would be fixed tomorrow.
Meanwhile, the Niagara of sewage keeps gushing, the grates keep opening, and Abel keeps at it with his rake.
Produced by Shachar Bar-On and Natalie Jimenez Peel. Broadcast associate, Maria Rutan. Edited by Matthew Lev.