In Arunachal Pradesh, a substantial conflict has emerged over the proposed development of 12 hydropower projects with a cumulative capacity of 11,523 MW, allocated to PSUs such as North Eastern Electric Power Corporation Ltd (NEEPCO) (2,620 MW), Satluj Jal Vidyut Nigam Ltd (SJVN) (5,097 MW), and National Hydroelectric Power Corporation (NHPC) (3,800 MW). Indigenous communities, particularly the Adi tribe from the Siang, Upper Siang, East Siang, West Siang, and Dibang Valley districts, have opposed these projects due to concerns about land submersion, environmental degradation, and cultural loss.

While the Tato-II HEP (700 MW), the Tato-I HEP (186 MW), the Heo HEP (240 MW), the Naying HEP (1,000 MW) and the Hirong HEP (500 MW) have been allotted to the NEEPCO, the Etalin HEP (3,097 MW), the Attunli HEP (680 MW), the Emini HEP (500 MW), the Amulin HEP (420 MW) and the Mihumdon HEP (400 MW) have been given to the SJVN. The Subansiri Upper HEP (2,000 MW) and the Subansiri Middle (Kamala) HEP (1,800 MW) have been allotted to the NHPC.

These projects were earlier entrusted upon private sector developers about 15 years ago, but they remained non-starters due to myriad of reasons. The state government, therefore, decided to rope in central hydro PSUs to give a push to the languishing projects.

On 12 August 2023, Arunachal Pradesh’s Power Commissioner, Ankur Garg, signed the agreements with the heads of the three CPSUs on behalf of the state government in Itanagar in the presence of Power and New and Renewable Energy Minister, R K Singh, State Chief Minister Pema Khandu, and his Deputy CM Chowna Mein.

Protesters voiced strong opposition to the government's plans, claiming a lack of consent, consultation, and warning of the disastrous consequences of such large hydropower projects, particularly a proposed 10,000 MW dam on the Siang River. They argue that these developments threaten both their land and ecological balance.

Water resources experts said that the 12 power projects in Arunachal Pradesh that were officially handed over to three Central public sector undertakings (CPSUs) on August 12 are "economically unviable".

A significant rally took place on 14 September 2023, in Geku Village, where over 7,000 attendees pledged against the Siang Dam, led by local priests. An Assam-based hydrologist, who did not want to be named, said these projects should not have been taken up in the first place. “Apart from being unviable, these guarantee disaster for Arunachal Pradesh and downstream regions in Assam,” he said.

Despite the protests, the government is committed to the projects. Manohar Lal, Union Minister of Power and Housing & Urban Affairs, on 8 July 2024, during his visit highlighted that Arunachal Pradesh has about 38 percent (about 50 GW) of India’s total hydropower potential. On the same day, activist lawyer Ebo Mili and Siang Indigenous Farmers’ Forum (SIFF) convener Dunge Apang were detained by the state government. They were released after over 10 hours of detention after signing a Rs 50,000 bond to keep peace until one year or the completion of ongoing inquiry.

On 23 May 2025, protests erupted in Beging village, Siang district, against the deployment of 100 Central Armed Police Force personnel for a pre-feasibility survey related to the SUMP. Villagers burned a hanging bridge to block access and demanded the removal of armed forces and drilling equipment. A few days later, the Ekhomey Mowo Welfare Society in Dibang Valley opposed the 400 MW Mihundo Hydroelectric Project, citing a lack of free, prior, and informed consent.

On 14 July 2025, over 1,000 villagers rallied in Geku, Upper Siang, reinforcing their opposition to the 11,000–12,500 MW SUMP. The Siang Indigenous Farmers’ Forum (SIFF) vowed to continue peaceful protests until the project is canceled.

Meanwhile, the Arunachal Pradesh government, under Chief Minister Pema Khandu, has declared 2025–2035 the "Decade of Hydropower," aiming to generate 58,000 MW with investments exceeding Rs 2 lakh crore. The government justifies these projects as vital for national interests, particularly to counter China’s upstream dams on the Yarlung Tsangpo River. However, Khandu has publicly stated that projects like the SUMP will not proceed without local consent.

Local communities fear the submersion of fertile lands, villages, and sacred sites, alongside environmental risks in a seismically active region rich in biodiversity. Rights groups, including Manipur’s Centre for Research and Advocacy, have condemned the government’s actions, particularly the detention of activists like Ebo Mili, as violations of indigenous rights, according to The Hindu.

“The deputy commissioner of Siang asked us not to oppose the dam,” said Tarok Siram, the headman of Parong village. “I told him to take the opinion of 116 families in my village. I pointed out that the homes of 43 families will be under waterif the dam is built here. The remaining families will have to be relocated.”