Dibang, India's largest hydel project in Arunachal Pradesh that got the green nod from the Union ministry for environment, forests and climate change last month, had to battle dissenting voices within the appraisal committee.
This came after the power ministry wrote to the environment ministry on September 16 this year, saying that reducing the dam height by 10 metres would require the least per Megawatt forest land and the increase in power tariff would also be negligible.
The project proponent had submitted an analytic report stating the implication of reduction of dam height by various proportions and concluded that a 10-metre reduction in dam height is optimum.
One of the FAC members raised objection that the justification by the power ministry and the company to reduce dam height by 10 metres does not "fully address the ecological concerns particularly in view of the rich biodiversity of the area". "Mega dams around the globe are known to have considerable upstream and downstream impacts both ecological and social," a member had noted.
However, the rest of the members said, according to the report, "Per Megawatt requirement of land and per unit power tariff were important objective parameters to appraise the projects from ecological and socio-economic objective with least possible subjectivity and likely bias in appraisal."
The NHPC report said reducing the dam height by 40 metres would entail a revenue loss of Rs 1,000 crore to the company and the power tariff will also go up significantly.
"With 10-metre height reduction, the increase in tariff is negligible. The tariff is Rs 5.66 per unit compared to Rs 5.64 at 10 metre height reduction. The tariff increases significantly with further height reduction. At 40-metre reduction, the tariff is Rs 6.24 per unit, which may make the project unviable," NHPC had said.
It also stated the total forest requirement per Megawatt will be the least if the dam height is reduced by 10 metres.
After the project was rejected by the FAC in July 2013, the power and environment ministries had met to decide that the project developer NHPC should submit a revised proposal to FAC.
The Arunachal Pradesh government in February this year had submitted a proposal, asking to reduce the dam height by 10 metres. This was, however, rejected by the FAC in its meeting in April this year.
Following this recommendation of the FAC, the environment ministry had written to the state government in August stating its decision to reject the nod to the project.
This followed a round of meetings between various Union government ministries including power, mine, steel and environment. On September 6, the environment ministry had requested the NHPC to submit a sensitivity analysis of reducing the dam height by 40 metres.
Many environmentalists had raised objections to the project clearance.