One evening last December, Pim Ranh walked down to the Sesan River to wash up after harvesting rice.
The water running through the northeast highlands of Cambodia was brown and muddy, but she was hot and needed to cool off. Later that night, Ranh woke up scratching at a rash on her hands and legs. Several months pregnant with her second child, she traveled hours by motorbike to find a medical clinic.
Weeks later, her scabs still covered in purple ointment, Ranh said she was worried her skin condition might hurt her baby. But, like so many others living downstream from the Yali Falls dam who reported rashes, stomach illnesses, and diarrhea since the dam's construction, she feels like there's no alternative to using the river to bathe and drink.
"I don't have a well at home," she said. "Even if the water looks dirty, I have to wash."
Built upstream in Vietnam and Laos, hydropower dams are rising up on the Sesan, Sekong, and Srepok Rivers that flow through Cambodia's northeast provinces, Ratanakiri and Stung Treng. Dams, such as the Yali Falls, have changed the water quality, killed whole species of fish, flooded villages, and wiped out large fields of rice.
These problems are compounded by what's happening in the nearby forests. There, armed guards stand in the thicket, threatening to arrest anyone who enters. The guards hack ax-cuts into the tree trunks, marking off ancestral land the government has sold to the highest bidder—usually a foreign company looking to start a lucrative plantation. The forests have traditionally served as a safety net for the indigenous people, providing a source of income during the "lean months" when the fish aren't spawning and the rice is too young to harvest. But when the government sells off the land, the safety net goes with it.
These dangerous circumstances threaten the very existence of the more than 66,000 people who live in these remote hills. What's worse, the indigenous people here lack any real political power. Many feel marginalized by the mainstream Khmer, who dominate the government and still associate the rural minorities with the genocide of the 1970s, which began as an agrarian revolution.
"The people here, they feel very isolated. They feel like no one from the outside will come to help them," said Kim Sangha, coordinator of the 3 S Rivers Protection Network (3SPN), an Oxfam America partner.
First the rivers
As the scorching sun sets on the Sesan River, the people of Taveng Lou village get to work. Men take out their fishing boats and pull in their nets. Women fill their watering cans and irrigate their gardens and rice paddies. Families wade into the shallows, bathing and collecting water for household use.
Vietnam's Yali Falls dam disrupts this daily routine. Since it became operational in 2001, the Cambodians living downstream have noticed dramatic changes. Unexpected water surges have eroded the shoreline, depositing silt, sand, and rocks in the deep pools where fish live. And the fluctuating water levels have either swept away nets or left them high and dry.
All in all, villagers here say they've seen a 70 percent drop-off in their fish catch.
"Before, you used to be able to put a pot on the fire, walk down to the river, and catch some fish—all before the water boiled," said Em Vuthy, deputy governor of Taveng District. "Now you can spend a whole day and get one fish."
Beyond reducing the number of fish, the dam has altered the way people farm along the Sesan River. Traditionally, the villagers depended on the overflow of the river to water their plants and rice during the wet season. During the dry season, they would plant different crops that could handle the heat and scarcity of water. But now people like Mean Trosh, a mother of seven who grows cabbage, watercress, pumpkins, red chilies, eggplants, and rice along the water, can't plan around the seasons; the dam creates unexpected floods. Trosh says she tries to plant on higher ground, but even those gardens and rice paddies have been destroyed.
"When the water level changes, it rises quickly and goes down quickly," 