CHANTHABURI, Thailand: Across a landscape where wild elephants roam and milky sap drips from endless rows of rubber trees, a decades-old tension is coming to a head.

Buddhist novices sweep dusty ground as smoke rises from small pits of burning rubbish. This is land that could soon be underwater.

Deep in the interior of eastern Thailand, a vast new reservoir could swallow thousands of hectares of forest, wildlife habitat and land occupied by rural communities.

The proposed Khlong Wang Tanot reservoir in Chanthaburi province – about four hours’ drive southeast of Bangkok – would store 99.5 million cubic metres of water, part of Thailand's efforts to secure supplies for its rapidly developing eastern seaboard.

But the project, first conceived in the 1990s, has become a flashpoint over the environmental and human costs of economic growth.

In August, Thailand’s Cabinet greenlit the project, with construction planned over seven years. But it cannot proceed without permission to use the protected forest in Khao Sip Ha Chan, including approval from the National Park Committee. The government has said newer environmental evidence can still be considered before that process is completed.

Two young monks sit at dusk in Ban Klong Yang village, which would be flooded under a proposed reservoir project.

Disagreement extends across government agencies, conservation groups and farming communities, with different views about whether the benefits of the reservoir outweigh the environmental and social costs.

The project has become a test of how Thailand balances its economic ambitions against commitments to protect forests, wildlife and communities living on the fringes of nature.

Among tin-roofed houses, flowering shrubs and coconut trees are those whose lives remain in flux.

The head of Ban Klong Yang village, Seeda Saengkla, lives inside the proposed reservoir area. Her community has 334 households and 654 residents. Many are prepared to accept the project but fear losing homes and livelihoods without sufficient compensation, she said. “Naturally, leaving would be heartbreaking. But many villagers are willing to make that sacrifice,” she said.

“What they want is for the government and relevant agencies to help them survive after relocating. They don't want to move somewhere else only to end up in debt. They don't want to feel abandoned.”The head of Ban Klong Yang village, Seeda Saengkla, lives inside the proposed reservoir area.

A GROWING THIRST Water shortages are not new to eastern Thailand. The Royal Irrigation Department (RID), a government agency, began studying the Wang Tanot watershed in the 1990s after serious dry-season shortages.

In the years since, those demands have only risen. Today, lucrative durian orchards increasingly spread across land once mostly planted with rubber, bringing with them a far greater thirst for water.

Thailand also faces growing uncertainty over rainfall with more intense downpours and periods of drought creating challenges for water planning.

Pornpimol Thongbo, a durian farmer in Kaeng Hang Maeo district, said her family's water requirements have increased as their trees mature. During the dry season, they rely on ponds and groundwater, sometimes buying additional water when rainfall is insufficient.

Inadequate water can mean losing an entire harvest, she said. Still, she questioned the need for another reservoir when many local farmers still cannot access water from those already built.

Three reservoirs have already been constructed in the watershed. Wang Tanot would be the fourth and largest, completing a system designed to improve agricultural water security and reduce downstream flooding.

The reservoirs are fed by rainfall and surface runoff flowing through the watershed, capturing water during the wet season for use during drier months.

“Right now, we still haven't seen anything that would convince local residents that building the reservoir will actually benefit them,” Pornpimol said.

RID's Thammanoon Innooch, director of the Large-Scale Irrigation Construction Office in the province, projected the new reservoir would help serve the farmers and households that need water most. That has energised other farmers in the area keen to see the project go ahead.

Thammanoon recognised that using protected forest land was a carefully considered issue and the project had been designed “to use only as much land within the national park as necessary”.

He acknowledged that up to 70 million cubic metres of surplus rainy-season runoff could eventually be transferred annually from the Wang Tanot watershed towards neighbouring Rayong province to support the wider EEC.

He said local water requirements would be met first and that the transfer volume would depend on rainfall and other conditions.

Industrial water requirements have risen substantially in the years since the reservoir was first conceived, with further expansion expected as Thailand courts a new generation of high-tech industries.

The weight of that need has locals questioning the fairness of the project, given what they say is a track record of being overlooked for water during dry periods.

“If it's for the benefit of the country, that's fine,” Pornpimol said. “But can local people benefit first? That's what matters to me.”Pornpimol Thongbo, a durian farmer in Kaeng Hang Maeo district, Thailand.

A "GOLDEN TIME" FOR INDUSTRY To drive along Thailand’s sprawling EEC area, which encompasses Chachoengsao, Chonburi and Rayong provinces, is to witness a landscape transformed.

Where fishing villages, rice fields and orchards once dominated, multilane expressways now cut through vast industrial estates, linking deep-sea ports, power stations and manufacturing plants. In recent times, the data-centre boom has landed in the EEC too.

Three major facilities are already operating or expanding, while nine more are under construction, according to industry tracking data.

Government figures also show that overall, 29 data-centre projects have applied for investment incentives in the EEC, making up more than half of all such applications nationwide.

Thailand sees it as an opportunity to revive economic growth and attract investment and higher-skilled jobs as projects spill over from more constrained markets such as Singapore and Malaysia, said Kwankamol Chittrakul, a civil engineer and expert in water resources management.

For now, developers were taking advantage of a window of opportunity before Thailand introduced stricter environmental regulations for data centres, she said. "It's a golden time. If you don't do it now, it will be more difficult in the future," she said. A data centre being constructed in Chonburi province, Thailand in October 2026.

The government is currently developing new regulations for data centres that would tighten oversight of their water and electricity consumption, environmental impacts and locations.

Still, hyperscale data centres add another major water consumer to a system already balancing agriculture, domestic demand and traditional industry.

Data centres require enormous computing power, generating heat that must be removed through cooling systems. Depending on the technology used, these facilities can consume substantial volumes of water.

Industry water demands in the EEC are expected to grow by 58 per cent between 2024 and 2037, according to Thailand's Office of National Water Resources.

The World Bank estimates that total annual water demand across the EEC's three provinces will reach 3.6 billion cubic metres by 2037.

And it warns that the region could face a water-supply shortfall of almost 40 per cent under average conditions, rising to 72 per cent in dry years, even with planned water infrastructure investments. The Eastern Economic Corridor faces severe water shortage projects in the years to come.

As supply lies in question, water availability is being actively used to convey confidence to would-be investors.

East Water, a major regional supplier, began supplying water to Bridge Data Centres in Chonburi in May, promoting its ability to provide uninterrupted supplies as a competitive advantage for Thailand's growing digital economy.

WHA Utilities and Power said this year that data centres can require 12 to 16 times as much water as conventional business customers. It is expanding water infrastructure and pursuing new contracts worth tens of millions of cubic metres annually to help cater to those requirements. Industrial-estate developers are also expanding reservoirs, pipelines and water-treatment facilities to accommodate new customers.

Even the agency overseeing the EEC has acknowledged the growing challenge, with its next development plan placing greater emphasis on securing water and electricity for the region's expanding high-tech industries. Managing water resources and supply across eastern Thailand is a major challenge for authorities.

Wang Tanot is one of several water infrastructure projects intended to strengthen supplies across eastern Thailand, where industrial demand is expected to keep growing.

Somnuck Jongmeewasin, research director at civil society organisation EEC Watch, questioned why Thailand continued to focus on finding new supply rather than better managing existing water.

He said that greater industrial water recycling, more efficient irrigation and improved distribution could ease pressure on resources, while ensuring local communities receive their fair share before water is diverted to industrial users.

And he warned that the expansion of privately supplied industrial water could leave communities at a disadvantage as competition for resources intensifies.

“All data centres have money. They can buy electricity. They can buy water. But local people cannot buy,” he said. “So, this water war is not fair." Locals in Ban Klong Yang are worried about being abandoned if their homes are flooded by the Wang Tanot project. Alternatives to Wang Tanot have been proposed.

The DNP has advocated a much smaller version of Wang Tanot that would flood only about 112 hectares of national park, combined with smaller reservoirs, greater storage at existing dams and more efficient water management.

Thammanoon said such measures could help, but would not provide enough water to meet projected demand.

The EEC Office is now working with the World Bank on expanding wastewater reuse, alongside measures to improve water efficiency and manage demand.

It also identified treated industrial wastewater reuse as an important way to reduce extraction from natural water sources and increase the resilience of EEC water supplies. An aerial view of the area that could be potentially flooded to construct the Wang Tanot reservoir.

ELEPHANTS IN THE ROOM Back in Wang Tanot, the push for more water threatens another increasingly scarce resource: space for wild elephants.

Beyond Ban Klong Yang village, the landscape opens up to scattered tree-lined hillocks and long stretches of unbroken forest. It is cool and shaded with breaks in the undergrowth and well-trodden dirt paths used by families of elephants.

The national park and surrounds here form part of an important wildlife corridor, used by more than 100 elephants searching for food and water and moving to different areas depending on the season.

Part of Thailand's Eastern Forest Complex, it connects larger protected forests. But during drier periods, the elephants travel farther and increasingly enter agricultural areas to feed, said Supakarn Kaewchot, a senior veterinarian for the Department of National Parks, Wildlife and Plant Conservation (DNP).

“If the reservoir affects existing feeding routes, elephants will have to find new ways to reach food sources,” she said.

There is concern that flooding established feeding grounds and movement corridors could potentially bring them into closer contact with people, said Rattanawat Chaiyarat, an associate professor at the Faculty of Environment and Resource Studies at Mahidol University.

“The question is,” he said, “where will they go when the surrounding areas of the Eastern Forest Complex are entirely dedicated to agriculture and industry?”Wild elephants captured by a trap camera in 2025 by officials at Khao Sip Ha Chan national park.

Human-elephant conflict in the eastern region was “already quite severe” and it remained uncertain how well local communities could handle increased contact in future, he said.

Elephants rely on generational memory to navigate seasonal feeding grounds. Altering these routes disrupts herd cohesion and leadership, said Padet Siridumrong, a veterinarian who works with large animals and wildlife.

“When herd structures collapse, elephants scatter into small groups and enter agricultural areas, triggering recurring conflicts. This will lead to continuous spending on mitigation projects without resolving the root cause,” said Padet, the director of Nern Plub Wan Animal Hospital in Chonburi.

RID acknowledged habitat loss could increase the risk of elephants moving into agricultural areas and communities. But Thammanoon said the reservoir is necessary to meet long-term water demand and that RID has incorporated measures to monitor wildlife movements and maintain habitat connectivity. Silchai Sae Jia says elephants visit and damage his rubber plantation on a daily basis. Silchai Sae Jia, a 73-year-old rubber farmer, is already fed up with the large mammals.

Elephants regularly cross his plantation, pulling down trees and frightening workers. Some have stopped working there because of the danger, he said.

His land would remain above the reservoir's waterline, but he fears losing the surrounding elephant habitat could make his property uninhabitable.

“Some people might say I'm lucky. They might say I'll have a beautiful view of the reservoir, a million-baht view. But that's not how I see it. I think I won't be able to live here anymore,” he said.

Silchai said he understood Thailand's desire for growth. But he questioned who would ultimately pay the price for that ambition.

“Your development should not come at the expense of people like me,” he said. “You should not use our shoulders as a stepping stone towards your own prosperity.”