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Massive invasive snakes are on the loose and spreading in Puerto Rico

News Feed
Tuesday, May 21, 2024

Quiere leer esta historia en español? Haga clic aquí.  Night had fallen in Cabo Rojo, a wildlife refuge along Puerto Rico’s southwestern coast, by the time we started our hike. Insects hummed from the grasses, green lizards slept in the trees, and resting water birds, spooked by our approaching footsteps, squawked and flew away. I scanned the canopy and the ground with a flashlight as my companions — a group of research biologists from a local university — had told me to. Hundreds of eyes reflected back at me from all directions: spiders. Moments later, as I neared the rocky coastline, my beam caught something even more unnerving. A few feet from where I stood, a large snake slithered along the forest floor. It was about 3 feet long and armored with a kaleidoscope pattern of green, black, and yellow scales. The snake was a boa constrictor. And it wasn’t supposed to be here. That late-night sighting was a glimpse into a much bigger problem in Puerto Rico: In recent years, three species of large invasive constrictors have been spreading across the island. Boa constrictors, which are native to South and Central America, are now common on the west side of the island. Meanwhile, reticulated pythons, the longest snakes in the world known to reach 30 feet, are abundant in the central mountains. In their native range of South and Southeast Asia, retics, as snake enthusiasts call them, have swallowed humans whole. Yet another invasive constrictor — the ball python — is starting to spread, too.  This is highly troubling for the island’s native animals, as well as for pets.  Boas and reticulated pythons are apex predators in Puerto Rico, meaning they are at the top of the food chain. And big snakes have big appetites. “It’s very, very bad,” said Alberto R. Puente-Rolón, a biologist at the University of Puerto Rico at Mayagüez and a leading authority on invasive snakes in the region. “We have a serious problem and a serious threat to the bird species here,” said Puente-Rolón, who was with me that night in Cabo Rojo.  This problem is especially clear in the wildlife refuge. Cabo Rojo is considered the most important stopover site for migratory species and shorebirds — including rare plovers and warblers — in the eastern Caribbean. These birds are critical pieces of complex and ancient island ecosystems. They help control the number of insects and other small animals that they consume, and they spread nutrients throughout the Caribbean (through their feces).  Invasive snakes are similarly threatening outside of Cabo Rojo and across the island, where there are thousands of other native species. Dozens of them are endemic, meaning they’re found nowhere else on Earth. These include birds like the native Puerto Rican parrot, one of the world’s rarest avian species. Because many trees rely on native birds to spread their seeds, losing the parrot would send ripples of destruction through the island’s native forests.  Scientists are also concerned that invasive constrictors will introduce diseases that harm the island’s native snakes, including the Puerto Rican boa, a federally endangered species that’s found only on the island. Other regions in the tropics have experienced the devastation wrought by invasive snakes. In Guam, the venomous brown tree snake — which is native to Papua New Guinea and Australia — wiped out 10 of the island’s 12 native forest birds after it was introduced to the territory in the mid-20th century. That loss is now threatening the future of Guam’s forests; like in Puerto Rico, many of the island’s trees need birds to spread their seeds. In south Florida, meanwhile, scientists have linked the spread of Burmese pythons to the severe decline of some native mammals like rabbits and foxes. The situation in Puerto Rico isn’t this extreme yet. While invasive constrictors are already widespread in some parts of the island, they are only just starting to fan out across Puerto Rico, scientists told me. That means local experts and environmental officials still have an opportunity to limit the destruction they can cause.  The big question now is whether Puerto Rico, an island in the Caribbean and a US territory, will act fast enough to stem the spread. It faces ongoing financial troubles — rooted in a long history of colonialism — as well as frequent natural disasters, which together stand in the way of progress. And as epicenters of the extinction crisis have demonstrated (see, Hawaii), the US often fails to spend money on interventions until native species have all but disappeared.  “Do we have to wait to press the panic button?” Puente-Rolón said. “Or can we be proactive?” Puerto Rico is filling up with invasive snakes On that April night in Cabo Rojo, which is about three and half hours from the capital of San Juan, we spotted two more invasive boas in the next hour. They were larger and wrapped around tree branches several feet above the ground.  Encountering three snakes in three hours is not normal. “Now you can understand the problem,” said Puente-Rolón, who has a handful of serpent tattoos on his upper body. (One is of a coral snake that he says almost killed him on a trip to the Amazon.) The boas weren’t far from a flock of shorebirds that nest by salt flats in the refuge. Last summer, researchers found three of them in the nesting area of least terns, small seabirds with black caps and smoky gray plumage that are declining in parts of the US. Two of the snakes were captured and dissected. One of them had the feathers of a young tern in its stomach.  “There is an ecological imbalance,” said Ana Román, who manages the Cabo Rojo National Wildlife Refuge. “These invasive species don’t belong.” Like nonnative species everywhere, the invasive snakes are here not because of their own actions but because of human beings. Pet traders have been selling constrictors and pythons in Puerto Rico for decades, although owning boa constrictors and retics without a permit is illegal. (The law, scientists told me, is not strictly enforced.) Pet snakes escape, experts warn. Plus, reckless owners sometimes release their animals into the wild when they get too big and hard to care for.  There are also potentially stranger routes of entry. In the ‘90s, a zoo just north of Cabo Rojo was robbed and, like a plot point in a cheap horror movie, a reptile cage was damaged and baby boas escaped, according to Puente-Rolón. (I couldn’t identify any Spanish or English news reports from the time to verify this claim, and the zoo has since closed. Puente-Rolón told me that he was at the zoo the day after the alleged break-in because he was studying one of its native snakes.)  In the last four months, a team of surveyors led by Fabián Feliciano-Rivera, a wildlife biologist, has captured more than 150 invasive boa constrictors in Cabo Rojo. Puente-Rolón estimates that there are roughly 13 of them per hectare (meaning more than 5 per acre) in the refuge, which is something close to extraordinary, he said.    It’s not just the number of snakes that’s surprising but that they’re in Cabo Rojo at all. The habitat here is extreme — it’s hot and dry, and the forest is sparse, leaving snakes with few places to hide. It’s certainly not like the humid forests full of fresh water that these snakes tend to prefer. To Feliciano-Rivera, that suggests boa constrictors are so abundant that they’re spreading to more challenging habitats.  As snakes disperse across the island, they’re showing up in backyards, chicken coops, and even cars. When people find them, they typically kill the animals or call local authorities, who retrieve the snakes and hand them over to DRNA, Puerto Rico’s wildlife agency. DRNA then brings them to a place called Cambalache.  A holding facility for exotic animals, Cambalache gets invasive snakes almost daily. Many of them come from the wild, though others are confiscated from breeders who sell them illegally.  Cambalache looked like a rundown zoo when I visited the facility one afternoon in April. A few dozen metal cages scattered around outside held nonnative monkeys. I saw large tubs of alligator-like reptiles called caimans. Cages inside of a small concrete building, meanwhile, were full of sugar gliders, adorable, palm-sized possums with large skin flaps that allow them to glide from tree to tree. Rangers had confiscated more than 50 of them from a breeder earlier in the week. Then there were the snakes. Tons of them. Outside in a wooden pen, roughly the size of a small storage shed, were some 30 writhing boas and reticulated pythons. One of the pythons was 11 feet long.  “My cats are gone, my chickens are gone. It’s a problem.” —Odalis Luna, python hunter Timothy Colston, an evolutionary biologist at the University of Puerto Rico, picked up one of the pythons. The snake coiled itself around his arm and, like a blood pressure cuff, caused the skin around it to bulge. (Colston, who’s been bitten by dozens of snakes, said it felt like a “little hug.”) No one knows how many invasive snakes there are in Puerto Rico. Hardly any scientific literature or public government documents have been published on the topic. That’s partly because the invasion is still new. It’s also because the island’s government and scientific institutions lack resources to study it (for a number of complicated reasons).   But there’s no doubt that invasive snakes are spreading.  One sign is the sheer number of boas in Cabo Rojo and Cambalache. Puente-Rolón has also noticed a surge in social media posts and news stories about sightings. In the last few years, scientists have also received intel from a small number of python hunters on the island, civilians who volunteer their time to capture invasive snakes. Just seven or so python hunters, also known as reticuleros, can catch 20 snakes a month, according to Jean P. Gonzalez Crespo, a doctoral researcher and invasive snake expert at the University of Wisconsin.  Do you have information about the spread of invasive species in Puerto Rico? Contact the author of this story here. I talked to a group of these reticuleros on a recent afternoon. They work normal jobs by day — one runs a pizzeria, another works in recycling — but by night they’re hunting snakes. It’s a way to safeguard their local community and the island’s rich biodiversity, said Odalis Luna, a reticulero who hunts with a small crew that includes her husband and their friend Wilson Maldonado. In the last three years, Luna said, they’ve captured around 170 snakes across several counties. Their reptile bounty includes babies, which suggests that invasive pythons are now breeding in the wild.  Finding the snakes is relatively easy, said Luna, who once caught a 17-foot reticulated python in front of her house. “We need to find more, because my cats are gone, my chickens are gone,” Luna said. “It’s a problem.” The uncertain fate of Puerto Rico’s native wildlife Scientists at the University of Puerto Rico are now racing to study the spread of invasive snakes. They still have a lot of unanswered questions — including where they are and which native animals they threaten most.  Those studies start by wrangling these scaly reptiles. When we’d come across an invasive boa in Cabo Rojo, one of the biologists would grab it using a specialized pole with a hook on the end and then put it in a pillowcase. The researchers also collect snakes from Cambalache, the DRNA holding facility, and from reticuleros.  Most of those snakes are then taken to a lab at the University of Puerto Rico.  Visiting the lab was a shock to the senses: Fluorescent lights lit up several tables, on which a handful of euthanized snakes were stretched out. It smelled of alcohol and rotting flesh. I watched as Colston and a group of students began slicing open the animals using surgical scalpels and poking around inside. On the most simple level, the researchers are trying to figure out what the snakes are eating. In some cases, it’s obvious: In late 2020, they pulled a cat out of a boa constrictor’s stomach, like some kind of sick magic trick.  But often, the team has to analyze the snakes’ feces. That morning, Mia V. Aponte Román, an undergraduate, squeezed poop out of a snake’s intestines and into a strainer. When she ran it under water, a handful of claws appeared. “Green iguana,” said Puente-Rolón, who was standing next to her, peering into the sink. Puente-Rolón’s team has examined the guts of more than 2,000 invasive boas, he said. That analysis — which hasn’t yet been published — suggests that the snakes are most frequently eating rats and mice, followed by a variety of birds and lizards, including iguanas.  When I first learned this, I wondered if the panic about invasive snakes was overblown. Rats and iguanas are invasive species, too. Aren’t the snakes just doing their own version of pest control?  This is not how ecology works. “The rats are going to end at some point,” Puente-Rolón says, meaning their numbers will eventually dwindle. “What we have learned from Guam with the brown tree snake is that mammals are going to disappear and then birds are the next target.” (Other places have learned the same lesson. In Hawaii, enormous colonies of free-ranging cats eat rats, but they’ve also decimated endangered birds.) Cutting open snakes also serves another, deeper purpose: helping scientists understand how exotic species adapt to their new homes once they arrive. Typically, scientists try to predict the harm that invasive animals will cause by looking at what they do in their native range. Where do they live? What do they eat? But according to Colston, who studies evolution, invasive species can also evolve after they move in, picking up new behaviors. Importantly, some of those behaviors may make these animals more damaging invaders. In their homeland, boas and pythons have to contend with other large snakes and predators, such as big cats. These are constraints that shape their behavior, and their evolution. Here in Puerto Rico, however, invasive constrictors have no natural predators and few competitors. Under these conditions, it’s possible that they may evolve traits that help them thrive in all kinds of habitats on the island. Colston’s team at the University of Puerto Rico will analyze DNA from snakes captured across the island to try and figure this out. They’re looking for ways in which the genome is changing — and how those changes might manifest in the animal’s body and behavior. There are actually hints that some of this evolution may already be underway. In Cabo Rojo, boa constrictors are smaller than those elsewhere on the island. Miniaturization could be an adaptation to drier conditions; smaller bodies retain water more easily. (It’s not clear whether the snakes are actually evolving to be smaller, generation after generation, or just failing to reach a larger size within their lifetimes. Colston’s work will likely provide answers.) A worst-case scenario is still avoidable That’s the good news. Sure, there are loads of giant snakes slithering through the forests and grasslands of Puerto Rico right now, not far from homes and rare species. But so far, the damage to the island’s native species has been minor. “We are in the phase that the impact is not that bad on our species,” Puente-Rolón said. To stop the snake problem from becoming a crisis, the state needs to act quickly, scientists say. Authorities — or an educated public — need to quickly ramp up efforts to remove snakes that are already in the wild and clamp down on the illegal pet trade.  To date, DRNA, the island’s wildlife agency, has done frustratingly little on both accounts, according to a number of biologists I spoke to for this story including Puente-Rolón, Feliciano-Rivera, and Gonzalez Crespo. They say the biggest issue is a lack of personnel and funding, they said. “They don’t have biologists, they don’t have the money,” Puente-Rolón said of DRNA. “If you have a forest infested with snakes and you only have one manager, what can he do?” —Ricardo Lopez-Ortiz, DRNA Instead of proactively removing snakes from the forest, DRNA rangers typically just respond to calls about sightings, and often only if someone is available, the scientists told me. Meanwhile, the wildlife holding facility is falling apart from a lack of upkeep and damage from hurricanes, a constant and worsening force of destruction.  Remarkably, it’s likely that snakes have actually escaped from Cambalache, several biologists told me. This isn’t difficult to fathom: On the morning I visited Cambalache, a monkey that had apparently broken out of its enclosure was rattling some of the other cages. What’s more is that officials at the municipal level, who are often the first to get calls about invasive snakes, have been slow to share information about where, exactly, they’re picking up the animals. That information would help scientists map the spread. “We really don’t get any help from the local government,” Gonzalez Crespo said.  I brought this up with Ricardo Lopez-Ortiz, who leads DRNA’s commercial fisheries division and is one of the few people at the agency who focuses on invasive species, including snakes. He acknowledged that there’s a lot to do, starting with getting more information. “We don’t know much,” he said of the spread of invasive snakes, adding that it’s possibly the “worst scenario” of any invasive species on the island. “We need to do more,” he told me. A lack of money isn’t the main issue, he said; the agency can get grants from the US Fish and Wildlife Service. But staff shortages have indeed been a serious problem, he said. “We don’t have enough personnel,” he told me. (More than a decade ago, when the country faced a financial crisis, the agency lost a large number of employees in an effort to cut government spending, he said. It’s been slow to refill the positions ever since, he added.)  “If you have a forest infested with snakes and you only have one manager,” Lopez-Ortiz said, “what can he do?”  (DRNA did not respond to a request for comment regarding the state of Cambalache facility. Lt. Ángel E. Atienza Fernández, a DRNA employee who oversees the Cambalache facility, also did not respond to direct requests for comment.) Puerto Rico also faces a number of forces that work against efforts to eradicate invasive species that are largely out of DRNA’s control, from natural disasters to the island’s much broader financial hardship. That leaves wildlife conservation lower on the government’s list of priorities. DRNA isn’t doing nothing. Lopez-Ortiz says the agency is developing a project in collaboration with biologists to study a number of invasive species including reticulated pythons and boas. That will involve gathering data from municipal authorities who are often the first to respond to snake calls. The agency is also working with government employees who manage state forests to help them identify and monitor invasive species.  “We have plans and we are working,” he said.  In the meantime, the heaviest burden of managing Puerto Rico’s snake problem falls on academic scientists — and the reticuleros, the python hunters. “This is going to be a problem in the long run,” Luna, one of the reticuleros, said. On my last night in Puerto Rico, Colston took me python hunting.  Like most of my experiences in Puerto Rico that week, it was the stuff of nightmares. Colston had gotten a tip earlier in the day from a DRNA official that we might find snakes in an abandoned sports stadium in the mountains south of San Juan. We drove to the stadium and, after dark, went inside.  The building was enormous, a huge ring of concrete surrounding a large, covered arena. Clumps of moss and plants grew in the stands. Old mattresses were strewn about. Bats flew overhead. And giant toads hopped around the stadium floor. Invasive snakes would fit right in. But we never saw any.  This left me feeling conflicted. I honestly wanted to see a python in the wild, mostly for the thrill of it. At the same time, I knew there was hope in their absence. Certainly one python-free night means nothing; snakes avoid people and can be hard to spot, even in areas with loads of them. Still, it was a subtle reminder of something important: It’s not too late to act.

Quiere leer esta historia en español? Haga clic aquí.  Night had fallen in Cabo Rojo, a wildlife refuge along Puerto Rico’s southwestern coast, by the time we started our hike. Insects hummed from the grasses, green lizards slept in the trees, and resting water birds, spooked by our approaching footsteps, squawked and flew away. I […]

Quiere leer esta historia en español? Haga clic aquí

Night had fallen in Cabo Rojo, a wildlife refuge along Puerto Rico’s southwestern coast, by the time we started our hike. Insects hummed from the grasses, green lizards slept in the trees, and resting water birds, spooked by our approaching footsteps, squawked and flew away.

I scanned the canopy and the ground with a flashlight as my companions — a group of research biologists from a local university — had told me to. Hundreds of eyes reflected back at me from all directions: spiders.

Moments later, as I neared the rocky coastline, my beam caught something even more unnerving. A few feet from where I stood, a large snake slithered along the forest floor. It was about 3 feet long and armored with a kaleidoscope pattern of green, black, and yellow scales.

The snake was a boa constrictor. And it wasn’t supposed to be here.

A boa constrictor winding through the branches of a tree.

That late-night sighting was a glimpse into a much bigger problem in Puerto Rico: In recent years, three species of large invasive constrictors have been spreading across the island. Boa constrictors, which are native to South and Central America, are now common on the west side of the island. Meanwhile, reticulated pythons, the longest snakes in the world known to reach 30 feet, are abundant in the central mountains. In their native range of South and Southeast Asia, retics, as snake enthusiasts call them, have swallowed humans whole. Yet another invasive constrictor — the ball python — is starting to spread, too. 

This is highly troubling for the island’s native animals, as well as for pets. 

Gloved hands hold a cat collar.

Boas and reticulated pythons are apex predators in Puerto Rico, meaning they are at the top of the food chain. And big snakes have big appetites. “It’s very, very bad,” said Alberto R. Puente-Rolón, a biologist at the University of Puerto Rico at Mayagüez and a leading authority on invasive snakes in the region. “We have a serious problem and a serious threat to the bird species here,” said Puente-Rolón, who was with me that night in Cabo Rojo. 

This problem is especially clear in the wildlife refuge. Cabo Rojo is considered the most important stopover site for migratory species and shorebirds — including rare plovers and warblers — in the eastern Caribbean. These birds are critical pieces of complex and ancient island ecosystems. They help control the number of insects and other small animals that they consume, and they spread nutrients throughout the Caribbean (through their feces). 

Invasive snakes are similarly threatening outside of Cabo Rojo and across the island, where there are thousands of other native species. Dozens of them are endemic, meaning they’re found nowhere else on Earth. These include birds like the native Puerto Rican parrot, one of the world’s rarest avian species. Because many trees rely on native birds to spread their seeds, losing the parrot would send ripples of destruction through the island’s native forests. 

Scientists are also concerned that invasive constrictors will introduce diseases that harm the island’s native snakes, including the Puerto Rican boa, a federally endangered species that’s found only on the island.

Other regions in the tropics have experienced the devastation wrought by invasive snakes. In Guam, the venomous brown tree snake — which is native to Papua New Guinea and Australia — wiped out 10 of the island’s 12 native forest birds after it was introduced to the territory in the mid-20th century. That loss is now threatening the future of Guam’s forests; like in Puerto Rico, many of the island’s trees need birds to spread their seeds. In south Florida, meanwhile, scientists have linked the spread of Burmese pythons to the severe decline of some native mammals like rabbits and foxes.

The situation in Puerto Rico isn’t this extreme yet. While invasive constrictors are already widespread in some parts of the island, they are only just starting to fan out across Puerto Rico, scientists told me. That means local experts and environmental officials still have an opportunity to limit the destruction they can cause. 

The big question now is whether Puerto Rico, an island in the Caribbean and a US territory, will act fast enough to stem the spread. It faces ongoing financial troubles — rooted in a long history of colonialism — as well as frequent natural disasters, which together stand in the way of progress. And as epicenters of the extinction crisis have demonstrated (see, Hawaii), the US often fails to spend money on interventions until native species have all but disappeared. 

“Do we have to wait to press the panic button?” Puente-Rolón said. “Or can we be proactive?”

Puerto Rico is filling up with invasive snakes

On that April night in Cabo Rojo, which is about three and half hours from the capital of San Juan, we spotted two more invasive boas in the next hour. They were larger and wrapped around tree branches several feet above the ground. 

Encountering three snakes in three hours is not normal. “Now you can understand the problem,” said Puente-Rolón, who has a handful of serpent tattoos on his upper body. (One is of a coral snake that he says almost killed him on a trip to the Amazon.)

The boas weren’t far from a flock of shorebirds that nest by salt flats in the refuge. Last summer, researchers found three of them in the nesting area of least terns, small seabirds with black caps and smoky gray plumage that are declining in parts of the US. Two of the snakes were captured and dissected. One of them had the feathers of a young tern in its stomach. 

“There is an ecological imbalance,” said Ana Román, who manages the Cabo Rojo National Wildlife Refuge. “These invasive species don’t belong.”

Like nonnative species everywhere, the invasive snakes are here not because of their own actions but because of human beings. Pet traders have been selling constrictors and pythons in Puerto Rico for decades, although owning boa constrictors and retics without a permit is illegal. (The law, scientists told me, is not strictly enforced.) Pet snakes escape, experts warn. Plus, reckless owners sometimes release their animals into the wild when they get too big and hard to care for. 

There are also potentially stranger routes of entry. In the ‘90s, a zoo just north of Cabo Rojo was robbed and, like a plot point in a cheap horror movie, a reptile cage was damaged and baby boas escaped, according to Puente-Rolón. (I couldn’t identify any Spanish or English news reports from the time to verify this claim, and the zoo has since closed. Puente-Rolón told me that he was at the zoo the day after the alleged break-in because he was studying one of its native snakes.) 

In the last four months, a team of surveyors led by Fabián Feliciano-Rivera, a wildlife biologist, has captured more than 150 invasive boa constrictors in Cabo Rojo. Puente-Rolón estimates that there are roughly 13 of them per hectare (meaning more than 5 per acre) in the refuge, which is something close to extraordinary, he said.   

It’s not just the number of snakes that’s surprising but that they’re in Cabo Rojo at all. The habitat here is extreme — it’s hot and dry, and the forest is sparse, leaving snakes with few places to hide. It’s certainly not like the humid forests full of fresh water that these snakes tend to prefer. To Feliciano-Rivera, that suggests boa constrictors are so abundant that they’re spreading to more challenging habitats. 

As snakes disperse across the island, they’re showing up in backyards, chicken coops, and even cars. When people find them, they typically kill the animals or call local authorities, who retrieve the snakes and hand them over to DRNA, Puerto Rico’s wildlife agency. DRNA then brings them to a place called Cambalache. 

A holding facility for exotic animals, Cambalache gets invasive snakes almost daily. Many of them come from the wild, though others are confiscated from breeders who sell them illegally. 

Cambalache looked like a rundown zoo when I visited the facility one afternoon in April. A few dozen metal cages scattered around outside held nonnative monkeys. I saw large tubs of alligator-like reptiles called caimans. Cages inside of a small concrete building, meanwhile, were full of sugar gliders, adorable, palm-sized possums with large skin flaps that allow them to glide from tree to tree. Rangers had confiscated more than 50 of them from a breeder earlier in the week.

Then there were the snakes. Tons of them.

Outside in a wooden pen, roughly the size of a small storage shed, were some 30 writhing boas and reticulated pythons. One of the pythons was 11 feet long. 

“My cats are gone, my chickens are gone. It’s a problem.”

—Odalis Luna, python hunter

Timothy Colston, an evolutionary biologist at the University of Puerto Rico, picked up one of the pythons. The snake coiled itself around his arm and, like a blood pressure cuff, caused the skin around it to bulge. (Colston, who’s been bitten by dozens of snakes, said it felt like a “little hug.”)

No one knows how many invasive snakes there are in Puerto Rico. Hardly any scientific literature or public government documents have been published on the topic. That’s partly because the invasion is still new. It’s also because the island’s government and scientific institutions lack resources to study it (for a number of complicated reasons).  

But there’s no doubt that invasive snakes are spreading. 

One sign is the sheer number of boas in Cabo Rojo and Cambalache. Puente-Rolón has also noticed a surge in social media posts and news stories about sightings. In the last few years, scientists have also received intel from a small number of python hunters on the island, civilians who volunteer their time to capture invasive snakes. Just seven or so python hunters, also known as reticuleros, can catch 20 snakes a month, according to Jean P. Gonzalez Crespo, a doctoral researcher and invasive snake expert at the University of Wisconsin. 

Do you have information about the spread of invasive species in Puerto Rico?

Contact the author of this story here.

I talked to a group of these reticuleros on a recent afternoon. They work normal jobs by day — one runs a pizzeria, another works in recycling — but by night they’re hunting snakes. It’s a way to safeguard their local community and the island’s rich biodiversity, said Odalis Luna, a reticulero who hunts with a small crew that includes her husband and their friend Wilson Maldonado.

In the last three years, Luna said, they’ve captured around 170 snakes across several counties. Their reptile bounty includes babies, which suggests that invasive pythons are now breeding in the wild. 

Finding the snakes is relatively easy, said Luna, who once caught a 17-foot reticulated python in front of her house. “We need to find more, because my cats are gone, my chickens are gone,” Luna said. “It’s a problem.”

The uncertain fate of Puerto Rico’s native wildlife

Scientists at the University of Puerto Rico are now racing to study the spread of invasive snakes. They still have a lot of unanswered questions — including where they are and which native animals they threaten most. 

Those studies start by wrangling these scaly reptiles. When we’d come across an invasive boa in Cabo Rojo, one of the biologists would grab it using a specialized pole with a hook on the end and then put it in a pillowcase. The researchers also collect snakes from Cambalache, the DRNA holding facility, and from reticuleros

Most of those snakes are then taken to a lab at the University of Puerto Rico. 

Visiting the lab was a shock to the senses: Fluorescent lights lit up several tables, on which a handful of euthanized snakes were stretched out. It smelled of alcohol and rotting flesh. I watched as Colston and a group of students began slicing open the animals using surgical scalpels and poking around inside.

On the most simple level, the researchers are trying to figure out what the snakes are eating. In some cases, it’s obvious: In late 2020, they pulled a cat out of a boa constrictor’s stomach, like some kind of sick magic trick. 

But often, the team has to analyze the snakes’ feces. That morning, Mia V. Aponte Román, an undergraduate, squeezed poop out of a snake’s intestines and into a strainer. When she ran it under water, a handful of claws appeared. “Green iguana,” said Puente-Rolón, who was standing next to her, peering into the sink.

Puente-Rolón’s team has examined the guts of more than 2,000 invasive boas, he said. That analysis — which hasn’t yet been published — suggests that the snakes are most frequently eating rats and mice, followed by a variety of birds and lizards, including iguanas. 

When I first learned this, I wondered if the panic about invasive snakes was overblown. Rats and iguanas are invasive species, too. Aren’t the snakes just doing their own version of pest control? 

This is not how ecology works. “The rats are going to end at some point,” Puente-Rolón says, meaning their numbers will eventually dwindle. “What we have learned from Guam with the brown tree snake is that mammals are going to disappear and then birds are the next target.” (Other places have learned the same lesson. In Hawaii, enormous colonies of free-ranging cats eat rats, but they’ve also decimated endangered birds.)

Cutting open snakes also serves another, deeper purpose: helping scientists understand how exotic species adapt to their new homes once they arrive.

Typically, scientists try to predict the harm that invasive animals will cause by looking at what they do in their native range. Where do they live? What do they eat? But according to Colston, who studies evolution, invasive species can also evolve after they move in, picking up new behaviors. Importantly, some of those behaviors may make these animals more damaging invaders.

In their homeland, boas and pythons have to contend with other large snakes and predators, such as big cats. These are constraints that shape their behavior, and their evolution. Here in Puerto Rico, however, invasive constrictors have no natural predators and few competitors. Under these conditions, it’s possible that they may evolve traits that help them thrive in all kinds of habitats on the island.

Colston’s team at the University of Puerto Rico will analyze DNA from snakes captured across the island to try and figure this out. They’re looking for ways in which the genome is changing — and how those changes might manifest in the animal’s body and behavior.

There are actually hints that some of this evolution may already be underway. In Cabo Rojo, boa constrictors are smaller than those elsewhere on the island. Miniaturization could be an adaptation to drier conditions; smaller bodies retain water more easily. (It’s not clear whether the snakes are actually evolving to be smaller, generation after generation, or just failing to reach a larger size within their lifetimes. Colston’s work will likely provide answers.)

A worst-case scenario is still avoidable

That’s the good news.

Sure, there are loads of giant snakes slithering through the forests and grasslands of Puerto Rico right now, not far from homes and rare species. But so far, the damage to the island’s native species has been minor.

“We are in the phase that the impact is not that bad on our species,” Puente-Rolón said.

To stop the snake problem from becoming a crisis, the state needs to act quickly, scientists say. Authorities — or an educated public — need to quickly ramp up efforts to remove snakes that are already in the wild and clamp down on the illegal pet trade. 

To date, DRNA, the island’s wildlife agency, has done frustratingly little on both accounts, according to a number of biologists I spoke to for this story including Puente-Rolón, Feliciano-Rivera, and Gonzalez Crespo. They say the biggest issue is a lack of personnel and funding, they said. “They don’t have biologists, they don’t have the money,” Puente-Rolón said of DRNA.

“If you have a forest infested with snakes and you only have one manager, what can he do?” 

—Ricardo Lopez-Ortiz, DRNA

Instead of proactively removing snakes from the forest, DRNA rangers typically just respond to calls about sightings, and often only if someone is available, the scientists told me. Meanwhile, the wildlife holding facility is falling apart from a lack of upkeep and damage from hurricanes, a constant and worsening force of destruction. 

Remarkably, it’s likely that snakes have actually escaped from Cambalache, several biologists told me. This isn’t difficult to fathom: On the morning I visited Cambalache, a monkey that had apparently broken out of its enclosure was rattling some of the other cages.

What’s more is that officials at the municipal level, who are often the first to get calls about invasive snakes, have been slow to share information about where, exactly, they’re picking up the animals. That information would help scientists map the spread. “We really don’t get any help from the local government,” Gonzalez Crespo said. 

I brought this up with Ricardo Lopez-Ortiz, who leads DRNA’s commercial fisheries division and is one of the few people at the agency who focuses on invasive species, including snakes. He acknowledged that there’s a lot to do, starting with getting more information. “We don’t know much,” he said of the spread of invasive snakes, adding that it’s possibly the “worst scenario” of any invasive species on the island. “We need to do more,” he told me.

A lack of money isn’t the main issue, he said; the agency can get grants from the US Fish and Wildlife Service. But staff shortages have indeed been a serious problem, he said. “We don’t have enough personnel,” he told me. (More than a decade ago, when the country faced a financial crisis, the agency lost a large number of employees in an effort to cut government spending, he said. It’s been slow to refill the positions ever since, he added.) 

“If you have a forest infested with snakes and you only have one manager,” Lopez-Ortiz said, “what can he do?” 

(DRNA did not respond to a request for comment regarding the state of Cambalache facility. Lt. Ángel E. Atienza Fernández, a DRNA employee who oversees the Cambalache facility, also did not respond to direct requests for comment.)

Puerto Rico also faces a number of forces that work against efforts to eradicate invasive species that are largely out of DRNA’s control, from natural disasters to the island’s much broader financial hardship. That leaves wildlife conservation lower on the government’s list of priorities.

DRNA isn’t doing nothing. Lopez-Ortiz says the agency is developing a project in collaboration with biologists to study a number of invasive species including reticulated pythons and boas. That will involve gathering data from municipal authorities who are often the first to respond to snake calls. The agency is also working with government employees who manage state forests to help them identify and monitor invasive species. 

“We have plans and we are working,” he said. 

In the meantime, the heaviest burden of managing Puerto Rico’s snake problem falls on academic scientists — and the reticuleros, the python hunters. “This is going to be a problem in the long run,” Luna, one of the reticuleros, said.

On my last night in Puerto Rico, Colston took me python hunting. 

Like most of my experiences in Puerto Rico that week, it was the stuff of nightmares. Colston had gotten a tip earlier in the day from a DRNA official that we might find snakes in an abandoned sports stadium in the mountains south of San Juan. We drove to the stadium and, after dark, went inside. 

The building was enormous, a huge ring of concrete surrounding a large, covered arena. Clumps of moss and plants grew in the stands. Old mattresses were strewn about. Bats flew overhead. And giant toads hopped around the stadium floor. Invasive snakes would fit right in.

But we never saw any. 

This left me feeling conflicted. I honestly wanted to see a python in the wild, mostly for the thrill of it. At the same time, I knew there was hope in their absence. Certainly one python-free night means nothing; snakes avoid people and can be hard to spot, even in areas with loads of them. Still, it was a subtle reminder of something important: It’s not too late to act.

Read the full story here.
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Toxic Pfas above proposed safety limits in almost all English waters tested

Exclusive: 110 of 117 bodies of water tested by Environment Agency would fail standards, with levels in fish 322 times the planned limitNearly all rivers, lakes and ponds in England tested for a range of Pfas, known as “forever chemicals”, exceed proposed new safety limits and 85% contain levels at least five times higher, analysis of official data reveals.Out of 117 water bodies tested by the Environment Agency for multiple types of Pfas, 110 would fail the safety standard, according to analysis by Wildlife and Countryside Link and the Rivers Trust. Continue reading...

Nearly all rivers, lakes and ponds in England tested for a range of Pfas, known as “forever chemicals”, exceed proposed new safety limits and 85% contain levels at least five times higher, analysis of official data reveals.Out of 117 water bodies tested by the Environment Agency for multiple types of Pfas, 110 would fail the safety standard, according to analysis by Wildlife and Countryside Link and the Rivers Trust.They also found levels of Pfos – a banned carcinogenic Pfas – in fish were on average 322 times higher than planned limits for wildlife. If just one portion of such freshwater fish was eaten each month this would exceed the safe threshold of Pfos for people to consume over a year, according to the NGOs.Pfas, or per- and polyfluoroalkyl substances, are a group of thousands of human-made chemicals used in industrial processes and products such as non-stick pans, clothing and firefighting foams. They do not break down in the environment and some are linked to diseases, including cancers and hormone disruption.Pfas pollution is widespread, prompting the EU to propose a new water quality standard that limits the combined toxicity of 24 Pfas to 4.4 nanograms per litre of water, calculated as PFOA-equivalents – a method that weights each substance according to its toxicity relative to PFOA, a particularly hazardous and well-studied carcinogen that is now banned.The EU is also planning to regulate about 10,000 Pfas as one class as there are too many to assess on a case-by-case basis and because none break down in the environment, but the UK has no plans to follow suit.Last week, environment groups, led by the Marine Conservation Society, wrote to ministers, urging a ban on all Pfas in consumer products and a timeline for phasing them out in all other uses. Now, public health and nature groups have joined forces to propose urgent measures to rein in pollution.“Scientists continue to identify Pfas as one of the biggest threats of our time, yet the UK is falling behind other countries in restricting them,” said Hannah Evans of the environmental charity Fidra. “Every day of inaction locks in decades of pollution and environmental harm … we’re asking the UK government to turn off the tap of these persistent forever chemicals.”They say the UK should align with the EU’s group-based Pfas restrictions and ban the substances in food packaging, clothing, cosmetics, toys and firefighting foams, following examples from Denmark, France and the EU. They want better monitoring, tougher water and soil standards and to make polluters cover the cost of Pfas clean-up.Emma Adler, the director of impact at Wildlife and Countryside Link, said: “Pfas are linked to an explosion of impacts for wildlife and public health, from cancers to immune issues. These new figures underline just how widespread Pfas pollution is and that Pfas regulation must be a much clearer priority in government missions to clean up UK rivers and improve the nation’s health.”Thalie Martini, the chief executive officer at Breast Cancer UK, said: “Evidence points to the potential for some Pfas to be related to health issues, including increasing breast cancer risk … millions of families affected by this disease will want the government to do everything they can to deliver tougher Pfas rules to protect our health.”Last year, 59 Pfas experts urged the government to follow the science and regulate all Pfas as a single class, warning their extreme persistence – regardless of toxicity – posed a serious environmental threat.skip past newsletter promotionThe planet's most important stories. Get all the week's environment news - the good, the bad and the essentialPrivacy Notice: Newsletters may contain info about charities, online ads, and content funded by outside parties. For more information see our Privacy Policy. We use Google reCaptcha to protect our website and the Google Privacy Policy and Terms of Service apply.after newsletter promotion“Countries like France and Denmark, the EU as a whole and many US states have taken strong action against Pfas pollution,” said Dr Francesca Ginley from the Marine Conservation Society. “The time is now for the UK to take a stand and show the leadership we need on Pfas pollution from source to sea.”Dr Shubhi Sharma of the charity Chem Trust said: “Too often with hazardous chemicals the world has ignored early warnings of harm and learned lessons far too late. Costs to tackle Pfas in the environment and address health impacts have a multi-billion pound economic price tag … the government must not delay.”An Environment Agency spokesperson said the science on Pfas was moving quickly and that it was running a multi-year programme to improve understanding of Pfas pollution sources in England. They added: “We are screening sites to identify potential sources of Pfas pollution and prioritise further investigations, whilst assessing how additional control measures could reduce the risks of Pfas in the environment.”A spokesperson for the Department for Environment, Food and Rural Affairs said: “The government is committed to protecting human health and the environment from the risks posed by Pfas. That’s why we are working at pace together with regulators to assess levels of Pfas in the environment, their sources and potential risks to inform our approach to policy and regulation.”

Breaking Down the Force of Water in the Texas Floods

Flash floods last week in Texas caused the Guadalupe River to rise dramatically, reaching three stories high in just two hours

Over just two hours, the Guadalupe River at Comfort, Texas, rose from hip-height to three stories tall, sending water weighing as much as the Empire State building downstream roughly every minute it remained at its crest.Comfort offers a good lens to consider the terrible force of a flash flood’s wall of water because it’s downstream of where the river’s rain-engorged branches met. The crest was among the highest ever recorded at the spot — flash flooding that appears so fast it can “warp our brains,” said James Doss-Gollin, assistant professor of civil and environmental engineering at Rice University.The Texas flood smashed through buildings, carried away cars and ripped sturdy trees out by the roots, dropping the debris in twisted piles when the water finally ebbed. It killed more than 100 people, prompted scores of rescues and left dozens of others missing. The deaths were concentrated upriver in Kerr County, an area that includes Camp Mystic, the devastated girls' camp, where the water hit early and with little notice.Water is capable of such destruction because it is heavy and can move fast. Just one cubic foot of water — imagine a box a bit larger than the size of a basketball — weighs about 62 pounds (28 kilograms). When the river rose to its peak at Comfort, 177,000 cubic feet — or 11 million pounds (5 million kilograms) of water — flowed by every second.“When you have that little lead time ... that means you can’t wait until the water level starts to rise,” Doss-Gollin said. “You need to take proactive measures to get people to safety.” Water as heavy as a jumbo jet A small amount of water — less than many might think — can sweep away people, cars and homes. Six inches (15.2 centimeters) is enough to knock people off their feet. A couple of feet of fast-moving water can take away an SUV or truck, and even less can move cars.“Suppose you are in a normal car, a normal sedan, and a semitrailer comes and pushes you at the back of the car. That’s the kind of force you’re talking about,” said Venkataraman Lakshmi, a University of Virginia professor and president of the hydrology section of the American Geophysical Union.And at Comfort, it took just over 15 minutes for so much water to arrive that not only could it float away a large pickup truck, but structures were in danger — water as heavy as a jumbo jet moved by every second.At that point, “We are past vehicles, homes and things can start being affected,” said Daniel Henz, flood warning program manager at the flood control district of Maricopa County, Arizona, an area that gets dangerous scary flash floods.The water not only pushes objects but floats them, and that can actually be scarier. The feeling of being pushed is felt immediately, letting a person know they are in danger. Upward force may not be felt until it is overwhelming, according to Upmanu Lall, a water expert at Arizona State University and Columbia University.“The buoyancy happens — it’s like a yes, no situation. If the water reaches a certain depth and it has some velocity, you’re going to get knocked off (your feet) and floating simultaneously,” he said. The mechanics of a flash flood The landscape created the conditions for what some witnesses described as a fast-moving wall of water. Lots of limestone covered by a thin layer of soil in hilly country meant that when rain fell, it ran quickly downhill with little of it absorbed by the ground, according to S. Jeffress Williams, senior scientist emeritus with the U.S. Geological Survey.A flash flood generally starts with an initial lead wave and then builds as rain rushes over the landscape and into the river basin. It may rise quickly, but the water still takes some time to converge. The water crumpled cars into piles, twisted steel and knocked trees down as if they were strands of grass. Images captured the chaos and randomness of the water’s violence.And then, not as fast as it rose, but still quickly, the river receded.Five hours after its crest at Comfort, it had already dropped 10 feet (3 meters), revealing its damage in retreat. A couple of days after it started to rise, a person could stand with their head above the river again.“Everything just can happen, very, very quickly,” Henz said.Associated Press writer Seth Borenstein in Washington contributed.The Associated Press receives support from the Walton Family Foundation for coverage of water and environmental policy. The AP is solely responsible for all content. For all of AP’s environmental coverage, visit https://apnews.com/hub/climate-and-environmentCopyright 2025 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.Photos You Should See - June 2025

South West Water allowed to invest £24m rather than pay £19m fine

Campaigners say Ofwat ‘subservient to industry and its rampaging pursuit of profit’ after illegal sewage dischargesSouth West Water has agreed to pay a £24m penalty for illegal sewage discharges into the environment from its treatment works.The regulator for the water and wastewater sector in England and Wales, Ofwat, says the company, which has 1.8 million customers in Cornwall, Devon, the Isles of Scilly and parts of Dorset and Somerset, is being penalised for dumping sewage in breach of its legal permit conditions. Continue reading...

South West Water has agreed to pay a £24m penalty for illegal sewage discharges into the environment from its treatment works.The regulator for the water and wastewater sector in England and Wales, Ofwat, says the company, which has 1.8 million customers in Cornwall, Devon, the Isles of Scilly and parts of Dorset and Somerset, is being sanctioned for dumping sewage in breach of its legal permit conditions.But there was anger over revelations on Thursday that the regulator had not imposed a direct fine on the company.South West Water put forward the suggestion that it would invest £20m to reduce sewage discharges at key storm overflows, spend £2m to tackle sewer misuse and misconnections, and another £2m to support local environment groups. This was accepted by Ofwat rather than imposing a fine of £19m.But Rob Abrams, the campaigns manager at Surfers Against Sewage, said allowing water companies to choose their own penalty was farcical.He said the situation “illustrates a water industry model that’s broken beyond repair, with government and regulators subservient to industry and its rampaging pursuit of profit, at any cost”.Ofwat said it had chosen this route rather than imposing a fine because it was satisfied that the company would carry out the work required to bring its infrastructure back into legal operation.“We have … concluded that it would be appropriate to accept the undertakings in lieu of the financial penalty we would otherwise impose in this case (£19m, 6.5% of its relevant turnover),” Ofwat said.The regulator carried out a two-year investigation into the company that found it had failed to upgrade its treatment works to prevent sewage discharges into the environment, failed to properly deal with the content of its sewers and failed to put in the resources to monitor its treatment works properly.The penalty is the latest in an ongoing investigation by Ofwat into several water companies into widespread illegal sewage dumping across the network from thousands of treatment plants.Penalties totalling more than £160m have already been imposed against Yorkshire Water, Thames Water and Northumbrian Water for widespread illegal sewage dumping from their treatment works.Lynn Parker, the senior director for enforcement at Ofwat, said the regulator had secured the £24m package and a commitment to put things right from the company.skip past newsletter promotionSign up to Business TodayGet set for the working day – we'll point you to all the business news and analysis you need every morningPrivacy Notice: Newsletters may contain info about charities, online ads, and content funded by outside parties. For more information see our Privacy Policy. We use Google reCaptcha to protect our website and the Google Privacy Policy and Terms of Service apply.after newsletter promotionBut Abrams said it amounted to a cynical PR exercise and an abdication of responsibility by Ofwat.“There is no transparency about how the money will be spent or whether it’s even enough,” he said.“Of the £4m pledged for environmental initiatives and local groups, we’ve been given no clarity on who will benefit or why.”The public and other stakeholders can make representations about the size of the penalty before it is finalised.

Oregon groundwater protection bill passes despite criticism that it’s too weak

Gov. Tina Kotek backed the bill to modernize Oregon’s failed groundwater pollution laws.

Legislators have just passed a groundwater protection bill that many nonprofit groups working on groundwater contamination said was too watered down to make a real difference. Gov. Tina Kotek backed the bill to modernize Oregon’s failed groundwater pollution laws. Kotek has been active in trying to speed up response to the three-decades-old groundwater contamination crisis in the Lower Umatilla Basin, where many residents with nitrate-contaminated domestic wells must rely on bottled drinking water. Until 2022, many people in the region had no idea they had been drinking contaminated water for years. Some still don’t know it because the state has yet to test all the affected wells. A state analysis also has shown that nitrate pollution in the area has worsened significantly over the past decade. Though the state has been testing wells and conducting public awareness campaigns, critics have accused the Oregon Department of Environmental Quality, Department of Agriculture and Water Resources Department of not doing enough to crack down on the pollution sources. Much of the nitrate contamination comes from fertilizer used by large farms, animal manure from local industrial dairies and feedlots and wastewater from food processing plants that are constantly applied to farm fields. Early versions of the bill laid out specific actions that state agencies would have to take once groundwater pollution had reached the level of a serious public health threat. But many of those actions were stripped out of the bill, leading environmental and social justice nonprofits to pull their support because they deemed the bill too weak to make a difference. Oregon Rural Action, the eastern Oregon nonprofit that has been instrumental in testing domestic wells and pushing the state to do more testing and to limit nitrate pollution, said industry groups representing polluters put pressure on the governor’s office, leading to major changes in the bill’s language. “The version passed on Friday no longer includes the tools, resources, and Legislative directives needed for agencies to exercise their authority to protect Oregon’s groundwater and enforce the law,”the group’s executive director, Kristin Anderson Ostrom, said in a statement. The governor’s office declined to comment.Kotek in January issued an emergency order allowing the Port of Morrow to again violate its water pollution permit and over-apply nitrogen contaminated water onto farmland. The port, which handles billions of gallons of nitrogen-rich water every year, said that it would have to pause operations and lay off workers if not for the emergency permit. In addition to the Lower Umatilla Basin, Oregon has designated two other areas – in northern Malheur County and the southern Willamette Valley – where elevated nitrate concentrations in groundwater pose a human health risk. Each one has an action plan to reduce nitrate concentrations in groundwater. Research has linked high nitrate consumption over long periods to stomach, bladder and intestinal cancers, miscarriages and thyroid issues. It is especially dangerous to infants who can quickly develop “blue baby syndrome,” a fatal illness.— Gosia Wozniacka covers environmental justice, climate change, the clean energy transition and other environmental issues. Reach her at gwozniacka@oregonian.com or 971-421-3154.

A rare glimpse inside the mountain tunnel that carries water to Southern California

In the 1930s, workers bored a 13-mile tunnel beneath Mt. San Jacinto. Here's a look inside the engineering feat that carries Colorado River water to Southern California.

Thousands of feet below the snowy summit of Mt. San Jacinto, a formidable feat of engineering and grit makes life as we know it in Southern California possible. The 13-mile-long San Jacinto Tunnel was bored through the mountain in the 1930s by a crew of about 1,200 men who worked day and night for six years, blasting rock and digging with machinery. Completed in 1939, the tunnel was a cornerstone in the construction of the 242-mile Colorado River Aqueduct. It enabled the delivery of as much as 1 billion gallons of water per day.The tunnel is usually off-limits when it is filled and coursing with a massive stream of Colorado River water. But recently, while it was shut down for annual maintenance, the Metropolitan Water District of Southern California opened the west end of the passage to give The Times and others a rare look inside. “It’s an engineering marvel,” said John Bednarski, an assistant general manager of MWD. “It’s pretty awe-inspiring.” The 16-foot-diameter San Jacinto Tunnel runs 13 miles through the mountain. While shut down for maintenance, the tunnel has a constant stream of water entering from the mountain. A group visits the west end of the San Jacinto Tunnel, where the mouth of the water tunnel enters a chamber. He wore a hard hat as he led a group to the gaping, horseshoe-shaped mouth of the tunnel. The passage’s concrete arch faded in the distance to pitch black.The tunnel wasn’t entirely empty. The sound of rushing water echoed from the walls as an ankle-deep stream flowed from the portal and cascaded into a churning pool beneath metal gates. Many in the tour group wore rubber boots as they stood on moist concrete in a chamber faintly lit by filtered sunlight, peering into the dark tunnel. This constant flow comes as groundwater seeps and gushes from springs that run through the heart of the mountain. In places deep in the tunnel, water shoots so forcefully from the floor or the wall that workers have affectionately named these soaking obstacles “the fire hose” and “the car wash.”Standing by the flowing stream, Bednarski called it “leakage water from the mountain itself.”Mt. San Jacinto rises 10,834 feet above sea level, making it the second-highest peak in Southern California after 11,503-foot Mt. San Gorgonio.As the tunnel passes beneath San Jacinto’s flank, as much as 2,500 feet of solid rock lies overhead, pierced only by two vertical ventilation shafts. Snow covers Mt. San Jacinto, as seen from Whitewater, in March. At the base of the mountain, the 13-mile San Jacinto Tunnel starts its journey. The tunnel transports Colorado River water to Southern California’s cities. During maintenance, workers roll through on a tractor equipped with a frame bearing metal bristles that scrape the tunnel walls, cleaning off algae and any growth of invasive mussels. Workers also inspect the tunnel by passing through on an open trailer, scanning for any cracks that require repairs.“It’s like a Disneyland ride,” said Bryan Raymond, an MWD conveyance team manager. “You’re sitting on this trailer, and there’s a bunch of other people on it too, and you’re just cruising through looking at the walls.” Aside from the spraying and trickling water, employee Michael Volpone said he has also heard faint creaking.“If you sit still and listen, you can kind of hear the earth move,” he said. “It’s a little eerie.”Standing at the mouth of the tunnel, the constant babble of cascading water dominates the senses. The air is moist but not musty. Put a hand to the clear flowing water, and it feels warm enough for a swim. On the concrete walls are stained lines that extend into the darkness, marking where the water often reaches when the aqueduct is running full. Many who have worked on the aqueduct say they are impressed by the system’s design and how engineers and workers built such a monumental system with the basic tools and technology available during the Great Depression.Pipelines and tunnelsThe search for a route to bring Colorado River water across the desert to Los Angeles began with the signing of a 1922 agreement that divided water among seven states. After the passage of a $2-million bond measure by Los Angeles voters in 1925, hundreds of surveyors fanned out across the largely roadless Mojave and Sonoran deserts to take measurements and study potential routes.The surveyors traveled mostly on horseback and on foot as they mapped the rugged terrain, enduring grueling days in desert camps where the heat sometimes topped 120 degrees.Planners studied and debated more than 100 potential paths before settling on one in 1931. The route began near Parker, Ariz., and took a curving path through desert valleys, around obstacles and, where there was no better option, through mountains.In one official report, a manager wrote that “to bore straight through the mountains is very expensive and to pump over them is likewise costly.” He said the planners carefully weighed these factors as they decided on a solution that would deliver water at the lowest cost. VIDEO | 02:45 A visit to the giant tunnel that brings Colorado River water to Southern California Share via Those in charge of the Metropolitan Water District, which had been created in 1928 to lead the effort, were focused on delivering water to 13 participating cities, including Los Angeles, Burbank and Anaheim. William Mulholland, Los Angeles’ chief water engineer, had led an early scouting party to map possible routes from the Colorado River to Southern California’s cities in 1923, a decade after he celebrated the completion of the 233-mile aqueduct from the Owens Valley to Los Angeles with the triumphant words, “There it is. Take it.”The aqueduct’s design matched the audaciousness of the giant dams the federal government was starting to build along the Colorado — Hoover Dam (originally called Boulder Dam) and Parker Dam, which formed the reservoir where the aqueduct would begin its journey.Five pumping plants would be built to lift water more than 1,600 feet along the route across the desert. Between those points, water would run by gravity through open canals, buried pipelines and 29 separate tunnels stretching 92 miles — the longest of which was a series of nine tunnels running 33.7 miles through hills bordering the Coachella Valley.To make it possible, voters in the district’s 13 cities overwhelmingly approved a $220-million bond in 1931, the equivalent of a $4.5-billion investment today, which enabled the hiring of 35,000 workers. Crews set up camps, excavated canals and began to blast open shafts through the desert’s rocky spines to make way for water.In 1933, workers started tearing into the San Jacinto Mountains at several locations, from the east and the west, as well as excavating shafts from above. Black-and-white photographs and films showed miners in hard hats and soiled uniforms as they stood smoking cigarettes, climbing into open rail cars and running machinery that scooped and loaded piles of rocks.Crews on another hulking piece of equipment, called a jumbo, used compressed-air drills to bore dozens of holes, which were packed with blasting power and detonated to pierce the rock. (Courtesy of Metropolitan Water District of Southern California) The work progressed slowly, growing complicated when the miners struck underground streams, which sent water gushing in.According to a 1991 history of the MWD titled “A Water Odyssey,” one flood in 1934 disabled two of three pumps that had been brought in to clear the tunnel. In another sudden flood, an engineer recalled that “the water came in with a big, mad rush and filled the shaft to the top. Miners scrambled up the 800-foot ladder to the surface, and the last man out made it with water swirling around his waist.”Death and delaysAccording to the MWD’s records, 13 workers died during the tunnel’s construction, including men who were struck by falling rocks, run over by equipment or electrocuted with a wire on one of the mining trolleys that rolled on railroad tracks. The Metropolitan Water District had originally hired Wenzel & Henoch Construction Co. to build the tunnel. But after less than two years, only about two miles of the tunnel had been excavated, and the contractor was fired by MWD general manager Frank Elwin “F.E.” Weymouth, who assigned the district’s engineers and workers to complete the project.Construction was delayed again in 1937 when workers went on strike for six weeks. But in 1939, the last wall of rock tumbled down, uniting the east and west tunnels, and the tunnel was finished. John Bednarski, assistant general manager of the Metropolitan Water District of Southern California, stands in a water tunnel near the end point of the larger San Jacinto Tunnel, which carries Colorado River water. The total cost was $23.5 million. But there also were other costs. As the construction work drained water, many nearby springs used by the Native Soboba people stopped flowing. The drying of springs and creeks left the tribe’s members without water and starved their farms, which led to decades of litigation by the Soboba Band of Luiseño Indians and eventually a legal settlement in 2008 that resolved the tribe’s water rights claims.The ‘magic touch’ of waterBy the time the tunnel was completed, the Metropolitan Water District had released a 20-minute film that was shown in movie theaters and schools celebrating its conquest of the Colorado River and the desert. It called Mt. San Jacinto the “tallest and most forbidding barrier.”In a rich baritone, the narrator declared Southern California “a new empire made possible by the magic touch of water.” “Water required to support this growth and wealth could not be obtained from the local rainfall in this land of sunshine,” the narrator said as the camera showed newly built homes and streets filled with cars and buses. “The people therefore realized that a new and dependable water supply must be provided, and this new water supply has been found on the lofty western slopes of the Rocky Mountains, a wonderland of beauty, clad by nature in a white mantle of snow.”Water began to flow through the aqueduct in 1939 as the pumping plants were tested. At the Julian Hinds Pumping Plant, near the aqueduct’s halfway point, water was lifted 441 feet, surging through three pipelines up a desert mountain. March 2012 image of the 10-foot-diameter delivery lines carrying water 441 feet uphill from the Julian Hinds Pumping Plant. (Los Angeles Times) From there, the water flowed by gravity, moving at 3-6 mph as it traveled through pipelines, siphons and tunnels. It entered the San Jacinto Tunnel in Cabazon, passed under the mountain and emerged near the city of San Jacinto, then continued in pipelines to Lake Mathews reservoir in Riverside County. In 1941, Colorado River water started flowing to Pasadena, Beverly Hills, Compton and other cities. Within six years, another pipeline was built to transport water from the aqueduct south to San Diego.The influx of water fueled Southern California’s rapid growth during and after World War II.Over decades, the dams and increased diversions also took an environmental toll, drying up much of the once-vast wetlands in Mexico’s Colorado River Delta. John Bednarski, assistant general manager of the Metropolitan Water District, walks in a water tunnel near the end point of the larger San Jacinto Tunnel. An impressive designToday, 19 million people depend on water delivered by the MWD, which also imports supplies from Northern California through the aqueducts and pipelines of the State Water Project.In recent decades, the agency has continued boring tunnels where needed to move water. A $1.2-billion, 44-mile-long conveyance system called the Inland Feeder, completed in 2009, involved boring eight miles of tunnels through the San Bernardino Mountains and another 7.9-mile tunnel under the Badlands in Riverside County.The system enabled the district to increase its capacity and store more water during wet years in Diamond Valley Lake, Southern California’s largest reservoir, which can hold about 260 billion gallons of water. “Sometimes tunneling is actually the most effective way to get from point A to point B,” said Deven Upadhyay, the MWD’s general manager.Speaking hypothetically, Upadhyay said, if engineers had another shot at designing and building the aqueduct now using modern technology, it’s hard to say if they would end up choosing the same route through Mt. San Jacinto or a different route around it. But the focus on minimizing cost might yield a similar route, he said.“Even to this day, it’s a pretty impressive design,” Upadhyay said.When people drive past on the I-10 in Cabazon, few realize that a key piece of infrastructure lies hidden where the desert meets the base of the mountain. At the tunnel’s exit point near San Jacinto, the only visible signs of the infrastructure are several concrete structures resembling bunkers. When the aqueduct is running, those who enter the facility will hear the rumble of rushing water. The tunnel’s west end was opened to a group of visitors in March, when the district’s managers held an event to name the tunnel in honor of Randy Record, who served on the MWD board for two decades and was chair from 2014 to 2018. Speaking to an audience, Upadhyay reflected on the struggles the region now faces as the Colorado River is sapped by drought and global warming, and he drew a parallel to the challenges the tunnel’s builders overcame in the 1930s. “They found a path,” Upadhyay said. “This incredible engineering feat. And it required strength, courage and really an innovative spirit.” “When we now think about the challenges that we face today, dealing with wild swings in climate and the potential reductions that we might face, sharing dwindling supplies on our river systems with the growing Southwest, it’s going to require the same thing — strength, courage and a spirit of innovation,” he said. A steep steel staircase gives access to a water tunnel near the end point of the larger San Jacinto Tunnel, which carries Colorado River water to Southern California.

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