A panel warned that large-scale tree felling across 2,733 hectares of dense forest in Arunachal Pradesh for the Subansiri hydroelectric project risks damaging forest structure, habitat continuity, biodiversity, and wildlife movement corridors. The Subansiri Lower Hydroelectric Project on the Assam-Arunachal border is one of India's largest run-of-river schemes. Forest diversion of this scale requires clearance under the Forest Conservation Act, raising questions about compensatory afforestation and cumulative ecological impact assessments.

The Subansiri Lower Hydroelectric Project (2,000 MW), being built by NHPC on the Subansiri river at the Assam-Arunachal Pradesh border, has faced prolonged controversy since its inception. Forest diversion at this scale triggers multiple regulatory layers that aspirants must understand.

Forest Conservation Act, 1980 (now Forest Conservation Amendment Act, 2023): Any diversion of forest land for non-forest purposes requires prior approval from the central government. For projects of this size, Stage I and Stage II forest clearances are mandatory, with conditions including Compensatory Afforestation (CA) — planting equivalent or double the area of diverted forest on non-forest or degraded land.

CAMPA (Compensatory Afforestation Fund Management and Planning Authority): Funds collected from project proponents for CA are deposited into CAMPA. The 2016 CAMPA Act restructured this into a statutory authority managing funds at national and state levels.

Environmental Impact Assessment (EIA): Under the Environment Protection Act, 1986, large hydro projects require EIA notification compliance, public hearings, and Expert Appraisal Committee clearance from MoEFCC.

Wildlife corridors and biodiversity: The Subansiri basin sits in one of the world's biodiversity hotspots — the Eastern Himalaya. Felling in such dense forests disrupts wildlife movement corridors, threatening species listed under the Wildlife Protection Act, 1972, and India's obligations under the Convention on Biological Diversity (CBD).

India's forest governance framework — especially the tension between development infrastructure and forest conservation — is a recurring UPSC and NABARD theme. The Subansiri project also illustrates cumulative impact assessment gaps in India's hydro-power corridor planning.