Salakpra is the country's first and largest wildlife sanctuary. But in 1991, a hydroelectric dam was built. It flooded villages and prime land. Local people and elephants turned against each other to fight for shrinking resources.
Belinda Stewart-Cox, who co-founded the Elephant Conservation Network, still remembers Salakpra as the pride of Thailand's protected ecosystem. That's why since 1999 she has been working to end the human-elephant conflict and repair broken ties.
"We want to reverse Salakpra's shame and restore its pride," Stewart-Cox says. "We want to make Salakpra a model of human-animal co-existence."
The Asian elephant is an endangered species, unlike its African cousin. Only 3,000 are left in the wild in Thailand; 150 live in Salakpra. Their habitat has been wrecked by human activities, such as logging and mining. Poachers that hunt and kill elephants have also been a big threat.
To make matters worse, villagers have moved deeper into elephant territory because of the reservoir.
Feeling trapped, some elephants raid farmers' crops to feed themselves. The biggest raid was on a crop of sugar cane, planted near River Kwai, in 1990, which elephants found irresistible. The river runs near Salakpra and is the animals' year-round source of water.
"It was a highly nutritious and elephant-friendly crop," Stewart-Cox says.
Locals were furious about the raid, but not for the first time; such problems began as early as 1982.
Most households in Salakpra are affected, but less than 5 per cent suffer serious problems. The elephants usually target crops, such as mangoes and maize, or corn.
"When these conflicts happen, elephants tend to lose," Stewart-Cox says. "The focus is all on the damage that elephants inflict on humans, but what about the other way round?"
Yet humans and elephants aren't fighting only over food. Water is also a limited resource.
Because villagers cannot access water from the nearby reservoir, they use the nature reserve.
Cattle herders let 3,500 livestock graze in the wildlife sanctuary alongside elephants. Locals bring in their herds at night, but some cattle owned by non-locals roam freely.
Stewart-Cox fears that this practice can spread disease.
"Elephants might catch tuberculosis from an ill cow," she says. Tuberculosis is a contagious disease to humans and animals.
Stewart-Cox says another serious problem is when villages block the herding routes of elephants.
Male elephants, known as mature bulls, usually travel to mate with females. But villages in the sanctuary sometimes block the paths used by elephants.
"[It's a problem] if bulls cannot disperse," Stewart-Cox says. "We can expect more crop-raiding, then bull-to-bull rivalries as they compete for females. There might be more deaths."
To tackle the problems, her organisation dug trenches and built electric fences around crops to protect them from elephants.
They also helped to train locals in crafts, such as sewing, and gave them money to start a co-operative. That way the locals don't have to rely on the nature reserve to make a living.
Meanwhile, a squad of armed forest rangers - dubbed the "environmental army" - patrols the sanctuary and drives poachers away. Cattle herders also receive government benefits to keep livestock away.
Now Stewart-Cox is studying how elephants roam. She hopes to establish wildlife corridors to prevent herds from being cut off from the main habitat.