China’s plans to build large hydropower stations in Tibet are designed to meet growing domestic demand for electricity and will not have a major impact on the ecosystem or on downstream water supplies, a senior government official said.

Tibet could become China’s biggest hydropower generator, with its rivers capable of carrying a total capacity of 140 gigawatts, around a quarter of the national total potential capacity, according to government estimates.

China last year started commercial operations of the Zangmu hydropower facility, the largest so far built in Tibet, and began building another plant in Shigatse earlier this year, also on the river Yarlung Zangbo, the upstream section of the transboundary Brahmaputra.

“Our hydropower development in Tibet falls under the country’s broad sector planning and meets strict standards. They will not have much impact on the environment, or any impact on downstream water supplies,” Wang Haizhou, vice chairman of the Tibetan Automous Region told reporters on Wednesday.

India and other downstream countries such as Vietnam have long expressed concern that China’s upstream dams could disrupt their water supplies.

Fresh concerns arose at the beginning of October when China’s official news agency Xinhua reported that a tributary of the Yarlung Zangbo had been blocked to facilitate the construction of the 4.95 billion yuan ($731 million) Laiho hydropower project, due to go into full operation in 2019.

The 2,900-km Brahmaputra flows southeast from Tibet through the Himalayas into northeast India’s Arunachal Pradesh state before entering Bangladesh and merging with the lower section of the Ganges, before it empties into the Bay of Bengal.

“The amount of water dammed is tiny compared to the total net river flows (in Tibet),” said Wang.

China hopes to make Tibet a key part of its cross-country “West-East Power Transmission” project designed to deliver electricity generated in the remote west to markets on the eastern coast through ultra-high voltage power lines.

So far the grid infrastructure connecting remote western regions with the rest of China remains deficient, forcing delays to large-scale projects like the one planned to be built on the Nu River in Yunnan province, developers have said.

China’s hydropower generators already have a surplus of capacity, and utilization rates at plants in the southwestern provinces of Sichuan and Yunnan have plunged as a result of slowing local demand and grid bottlenecks.

Researchers from China’s Academy of Science involved in ecological protection work in Tibet said on Wednesday that the region should curb small hydropower plants and promote more solar and wind power, echoing a policy that’s already in place in neighbouring hydropower-rich Sichuan province.

Tibet’s existing two major hydropower plants, the Zangmu and the Guoduo project on the upper reaches of the Lancang (Mekong) river, have a combined installed capacity of 657 megawatts, 0.2 percent of China’s total hydropower capacity.

China’s total hydropower capacity stood at more than 300 gigawatts last year following the completion of several large-scale dams in southwest China, raising concerns from environmental groups that water supplies in downstream countries such as Vietnam will be disrupted.