Thailand's Khlong Wang Tanot reservoir plan stirs debate over water, wildlife and data centres
Thailand has approved a major reservoir in Chanthaburi province to supply water for industry, including a data-centre boom. The project threatens protected forest and elephant habitat, and has divided local communities, conservationists and government agencies over its costs and benefits.
Thailand's Cabinet in August greenlit the Khlong Wang Tanot reservoir in Chanthaburi province, about four hours' drive southeast of Bangkok, a project first conceived in the 1990s. The reservoir would store 99.5 million cubic metres of water and is part of efforts to secure supplies for the Eastern Economic Corridor (EEC), where industrial demand is rising sharply. Construction is planned over seven years, but the project cannot proceed without permission to use protected forest in Khao Sip Ha Chan, including approval from the National Park Committee.
The reservoir would be the fourth and largest in the Wang Tanot watershed, designed to improve agricultural water security and reduce downstream flooding. Thammanoon Innooch, director of the Large-Scale Irrigation Construction Office at the Royal Irrigation Department (RID), said the project would help serve farmers and households that need water most. He acknowledged that up to 70 million cubic metres of surplus rainy-season runoff could eventually be transferred annually to neighbouring Rayong province to support the EEC, though local needs would be met first.
Water demand in the EEC is expected to grow by 58 per cent between 2024 and 2037, according to Thailand's Office of National Water Resources. The World Bank estimates total annual water demand across the EEC's three provinces will reach 3.6 billion cubic metres by 2037, and warns of a supply shortfall of almost 40 per cent under average conditions, rising to 72 per cent in dry years. Data centres are a major new consumer: three facilities are already operating or expanding in the EEC, nine more are under construction, and 29 projects have applied for investment incentives, making up more than half of such applications nationwide.
Local residents have mixed feelings. Seeda Saengkla, head of Ban Klong Yang village, which lies inside the proposed reservoir area, said many of the 334 households are willing to make way but fear losing homes and livelihoods without sufficient compensation. Durian farmer Pornpimol Thongbo questioned why another reservoir is needed when many farmers still cannot access water from existing ones. “Right now, we still haven't seen anything that would convince local residents that building the reservoir will actually benefit them,” she said.
The national park and surrounding forest form part of an important wildlife corridor used by more than 100 elephants. Supakarn Kaewchot, a senior veterinarian at the Department of National Parks, Wildlife and Plant Conservation (DNP), said flooding established feeding routes could force elephants to find new paths, potentially bringing them into closer contact with people. Rattanawat Chaiyarat, an associate professor at Mahidol University, noted that human-elephant conflict in the region is already severe.
The DNP has proposed a much smaller version of the reservoir 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 would not provide enough water to meet projected demand. The EEC Office is working with the World Bank on expanding wastewater reuse and improving water efficiency, but critics argue that Thailand should focus on managing existing water better rather than building new supply.
