To realise India's goal to generate 50,000 MW of hydroelectric power, three major projects are planned along the Subansiri river: the 2,000 MW Upper Subansiri Hydroelectric Project (HEP), the 1,800 MW Kamala Hydroelectric Project (formerly known as the Subansiri Middle Hydroelectric Project), and the 2,000 MW Subansiri Lower Hydroelectric Project (SLHEP).

The SLHEP is located at Gerukamukh, straddling the border between Assam and Arunachal Pradesh, with the dam's left bank in Assam and the right bank and powerhouse in Arunachal Pradesh. The Subansiri Upper project is located in the Upper Subansiri district, while the Kamala Project is located in Kamle district.

Despite its strategic importance, the project has faced significant opposition from local communities in both states due to concerns over environmental impacts and displacement.

In 1954, severe flooding in Upper Assam led to the proposal of a storage reservoir on the Brahmaputra River to control future floods. The project stalled due to budget constraints and political opposition, particularly from Arunachal Pradesh's Chief Minister Gegong Apang, who feared displacement. By 1995, the project evolved into six smaller dams on the Subansiri and Dibang rivers. However, when construction began in 2005 under the National Hydro Project Limited (NHPCL), local protests erupted over inadequate environmental assessments.

Despite repeated halts and legal challenges, including an interim order in 2015 that allowed only repair work, the National Green Tribunal (NGT) eventually green-lit the project in 2019. Activists claimed bias within the expert committees, but their pleas were dismissed, and the Supreme Court upheld the decision. The original flood management goal was deemed compromised by experts, yet NHPCL announced the project's completion by March 2022, after years of delays due to local resistance.

In June 2022, heavy rains in Arunachal Pradesh caused a dam overflow, flooding about a hundred villages in Assam. A flood struck the dam site on 24 September 2022, causing parts of the guard wall to collapse. This led to protests demanding the project's cancellation. Subsequent landslides on October 11 and October 27 triggered further protests. These events are not exceptional. The dam site was hit and damaged by floods in [2019 ](https://www.facebook.com/watch/?ref=search&v=2057780621197403&external_log_id=9b0a1ff5-fd76-4095-9ad0-4fb7fc8628d9&q=nhpc subansiri landslide)and 2020 as well. In August 2021, following heavy rains in Arunachal Pradesh, a few score villages in Lakhimpur were flooded after water rolled over the dam. They have prompted residents and political and environmental activists to call the project “a ticking water bomb”. 

“We have repeatedly demanded that the government stop this water bomb in the interest of public life and security,” said Nirmal Payeng, a resident of Lakhimpur and an activist with the Krishak Mukti Sangram Samiti (KMSS). “Otherwise, there will be intense protests. The guard wall has already collapsed. It is proven that the people are not secure from the NHPC’s water bomb.”

In the Ghunaxuti area in North Lakhimpur, 50 km downstream from the SLHEP dam site, members of the indigenous Mising community alleged that flood frequency and erosion on the Subansiri River had aggravated since the dam’s construction resumed in 2019, forcing people to relocate.

“Whenever they release water, it creates an emergency situation here. It becomes very difficult to protect cattle and houses,” said Dinesh Kutum, a resident of Balibheta village in Ghunasuti. “Agriculture is finished. Hundreds of acres of fields have gone underwater. The river’s erosion is eating farmland.”

Ananta Mihi from Balibheta claimed that the dam released a large amount of water in late September, causing increased downstream current intensity. This exacerbated the erosion of the Subansiri River, leading to the relocation of residents living nearby.

The family of Madhurjya Pegu was dismantling their residence, which stood about 10 meters from the river. They estimated the river could take one or two weeks to reach their home. They had found a small plot of land 2 km away where the house could be rebuilt, Pegu said. Four other families had relocated in the last seven days.

Discussing the environmental implications of the drying river, farmers' rights activist of KMSS, Bidyut Saikia said, “The Subansiri river is home to 239 varieties of fishes. Some of the varieties are locally known as Xalodi Pithia and Bam Seni. There were 28 Gangetic River Dolphins as well, out of which we have already recovered the lifeless body of one of them. There are some pockets with 2-3 inches of water, but you can easily cross the river with the aid of a motorbike now. Soon, the tube wells that draw water from the river will dry up. Vegetation around the riverbanks will be affected.”

While speaking to LCW, Saikia reiterated, "Since 16 December 2011, project work was stopped due to a movement. In 2014, before Narendra Modi became Prime Minister, he promised to only build small dams. However, after the BJP government was formed, they started the project in 2015 and cunningly completed it during the Covid-19 lockdown. Concerns about safety and access to the area still remain. Most of the communities in the downstream areas will be highly impacted, especially the Mising communities."

On 21 July 2023, the government of Arunachal Pradesh approved the allotment of the 2000 MW Subansiri Upper Hydroelectric Project and the 1800 MW Kamala Hydroelectric Project to NHPC Limited. A month later, on 12 August 2023, the Memorandum of Agreement for developing the Subansiri Upper and Kamala projects was formalised.