Over coffee and cigarettes on a humid day in Phnom Penh, the capital of Cambodia, two photographers hatched a pipe dream: Wouldn’t it be great, they thought, to escape their run-of-the-mill assignments, buy a wooden longboat, and travel up the Mekong, from its delta in Vietnam to its source on the Tibetan Plateau?

“To be honest, it was a boys’ trip at first,” Gareth Bright, a South African photographer based in Phnom Penh, told Sixth Tone. “The idea of driving a boat up the Mekong was total Conrad-esque and ‘Apocalypse Now.’”

From its source in the Tibetan Plateau, the Mekong, known as the Lancang in China, drops more than 5,000 meters as it flows southeast, making its way through Laos, Thailand, Cambodia, and eventually forming the Mekong Delta in southern Vietnam before emptying into the South China Sea. It’s the sixth-largest river in the world and, with 1,100 species of fish, trails only the Amazon in biodiversity. But having worked in Southeast Asia for several years, Bright and his Canadian partner, Luc Forsyth, also a widely published photographer, wanted to peek behind the facts and figures to learn how the waterway affects the lives of the tens of millions of people who live along it.

With backing from Lien AID, an NGO focusing on water and sanitation, the two bought a wooden long-tail boat, “sort of” learned to sail it, navigated it to the Tonle Sap lake in northwestern Cambodia, and started a blog: A River’s Tail.

After two years and thousands of kilometers traveled by boat, car, and plane, they reached their goal. Draped in thick fur coats, they had made it to the spiritual source of the Mekong. In an interview with Sixth Tone, Bright and Forsyth shared what they’ve learned about Western ideas of development, what it means to be selfless, and how the river’s delicate ecosystem connects people from Yunnan and Tibet in southwestern China with those as far away as southern Vietnam. The interview has been edited for brevity and clarity.

Sixth Tone: One river, many countries. What differences did you see in the way humans interact with the Mekong?

Luc Forsyth: What was really surprising to me was that compared to the Southeast Asian stretch, the Chinese didn’t really use the Mekong at all. In Cambodia, Laos, and Vietnam, you have people out there on fishing boats every single day directly interacting with the water. For most of Yunnan — and especially Tibet — the river was flowing through deep valleys and gorges, and for a lot of people it was moving so fast that there wasn’t much they could do with it, even if they wanted to.

Sixth Tone: In downstream countries, there are complaints about China’s push for new hydropower projects on the Mekong. Has your journey changed your perception of this development at all?

Luc Forsyth: I came to understand the Chinese mentality toward the river in a sense that it didn’t really do anything for the people directly. While in Cambodia, half of the people’s food and 70 percent of their protein is coming from this river, so when they are destroying it, you think, “What are you doing? Why are you building a dam here?”

Gareth Bright: We were traveling backwards, so we had already seen all the damage and destruction downstream. By the time we got to Yunnan, we had all this internal anger because we had already seen the damage and destruction downstream. In China, [dams] make perfect sense. But when you’re dealing with a transboundary river, and you’re at the top, you have to consider what’s going to happen at the bottom.

Sixth Tone: How much awareness do the people living along the Mekong have of the effects of human activity on the river?

Luc Forsyth: In Vietnam, almost nobody was able to fish there. We met shrimp farmers who had been fishermen but realized they couldn’t make a viable living anymore, so they went inland and started shrimp farms and fish farms.

On the flip side, in Zadoi, the second-to-last place we visited in Tibet, the villagers had so little awareness of what was going on that one of them actually asked us if the Mekong flows through Beijing. And yet they were voluntarily fishing plastic out of the water without any direct knowledge of who else depends on it. But they knew that other people were using the river, and so they were trying to keep it clean. After a year and a half of seeing some pretty terrible stuff, we were having people ask: “So, how is it going down there?” They don’t know anything about what’s outside their little space. And to hear that, we wanted to cry — that was the saddest thing I ever heard.

Sixth Tone: So in some places, there is a sense that the river is a shared responsibility, even if the basic understanding of how many people and species depend on it is lacking?

Gareth Bright: The whole thing is really crazy. The Tibetan Plateau is the largest freshwater source in world, and one of the most heavily impacted by climate change. And the people who are from there are telling you it’s changing: The grass is a little bit lower this year; the snow isn’t high enough. The monks at this monastery had been collecting water samples for 10 years, but they don’t have anybody to actually analyze them. But their brain tells them, “We need to keep this water to check it in the future, and maybe someday, someone will come and help us.” There was this foresight that in all honesty I had not seen anywhere else along the river. The last person we spoke to there is a volunteer at the source. You drive there, and there is no road — but eventually you get to this little shack, and this guy is living there with his kid, and every two or three years he and his brother swap out, and they just look after the source. And when tourists come, they just make sure that people aren’t doing anything bad. They weren’t getting paid — it’s not a job, so there’s no financial reason to do it.

Sixth Tone: You must have thought about reaching the spiritual source a lot, and I guess you had built up a lot of expectations. When you got there, was it what you had expected, or was it disappointing?

Luc Forsyth: I quit smoking at the source…

Gareth Bright: There weren’t any cigarettes there.

Luc Forsyth: Well, it was really cold — we were exhausted. We looked at it, we walked around, we shot some pictures, Gareth and I hugged each other, but it was a little “meh.” It was very hard to accept and hard to internalize. It’s only been within the last month [November] that I’ve had a minute to breathe and realize what happened. There’s a guy guarding the source on his own time, living there with his kid in this stone house — that’s incredible.

Sixth Tone: What changed between then and now?

Gareth Bright: It’s like an old relationship: When you’re in it, you’re in it, and afterward, when you have the opportunity to step back, you realize what it all meant. The people along this river are some of the kindest, most welcoming people I’ve ever met. And people say that of Southeast Asian people, but when we went to China — and I had not been before — the people were just delightful. I never posed for so many selfies and portraits in my life. I was offered a cup of tea everywhere; they welcomed us into their homes.

In the lower basin, you’re dealing with issue after issue, problem after problem. Within days of being in Vietnam, we met a farmer on a small island who had given up rice farming and started shrimp farming because of the salination of the river. Because of the dams, the river is not flowing as heavily as it should, so the sea is coming in, and so there is massive erosion, and the mangroves are being destroyed. And this shrimp farmer is doing whatever he can to fix it. The people on the ground are suffering.

Once the river shifts to the Lancang, it just becomes this highway to culture and old traditions and beautiful old stories, and I think that is what I’ve taken from it more than anything.

We have these huge, complex Western ideas which I’ve had to learn to just shut out. We have this Western point of view of what development means and what construction means, and how it can degrade the environment — but we need that development. People in Cambodia certainly need that development. And you have to take a step back. What I took away from these encounters is that you’ve just got to treat everything gently. You have to tread gently on our planet. That’s from all the people I’ve met, that’s the lesson: Tread gently on earth.

In collaboration with A River’s Tail, a yearlong exploration of the Mekong, Sixth Tone will publish a series of articles on life along the river in Yunnan province and the Tibetan Plateau. For more stories from the Mekong, visit www.ariverstail.com.

(Header image: Construction is underway on a bridge that will span the Mekong River in Cizhong, Yunnan province, Feb. 14, 2016. Luc Forsyth for Sixth Tone)