Context: Recently, the Kerala government has issued a fresh no-objection certificate (NOC) for the state electricity board to proceed with the implementation of the proposed Athirapally hydro-electric project, which had been shelved several times in the past due to protests by green activists.
Background

• Silent Valley was an ecological movement with huge mass participation, that forced the Kerala government to abandon dam construction across the Kunthri River in Palakkad district during the late 1970s and early 1980s.
• The proposed project will be seventh dam along the 145-kilometre course of the Chalakudy river.
• This is a death knell for what remains of endemic species of flora and fauna in the Athirappally-Vazhachal region.

Key Points

• The total installed capacity of AHEP is 163 MW and the project is supposed to make use of the tail end water coming out of the existing Poringalkuthu Hydro Electric Project that is constructed across the Chalakudy river.
• AHEP envisages diverting water from the Poringalkuthu project as well as from its own catchment of 26 sq km.
• Kerala state government has given a no-objection certificate (NOC) to the Kerala State Electricity Board (KSEB) for a period of seven years and has permitted it to proceed with the project’s implementation.
• KSEB officials are confident that they can manage approval from the Ministry of Environment, Forest and Climate Change as it was approved in 2012 by an Expert Appraisal Committee (EAC) for river valley and hydro-electric projects.
• EACs are constituted for giving environmental clearance under the Environmental Impact Assessment (EIA).

Biodiversity of that region

• Around 168 hectares of biodiversity-rich forests in the Western Ghats would be submerged if the project got implemented.
• “Athirappally is home to some rarest species of birds, animals and plant species.
• The project would be an environmental disaster in the making and would sever the only link between the Peechi Vazhani Wildlife Sanctuary and the Idamalayar basin of the Periyar river.
• The vital elephant corridor between the Parambikulam Sanctuary and the Pooyamkutty forests would also be affected.
• Apart from being home to hornbills, tigers and leopards, the forests also host the Nilgiri langur, the lion-tailed macaque and the rare Cochin forest cane turtle.

Environmental Threats

• Athirappally is home to some rarest species of birds, animals and plant species which will be impacted.
• Apart from being home to hornbills, tigers and leopards, the forests also host the Nilgiri langur, the lion-tailed macaque and the rare Cochin forest cane turtle.
• Fish varieties in the Chalakudy river would be impacted.
• Kadar tribal settlements in the forests will be dismantled and displaced. The move seems to be violative of the forest rights granted to the Kadars under the Forest Rights Act, 2006.
• It would sever the only link between the Peechi Vazhani Wildlife Sanctuary, Thrissur and the Idamalayar basin of the Periyar river.

About Chalakudy River

• It is the fifth longest river in Kerala and flows through Palakkad district, Thrissur District and Ernakulam District of Kerala. 
• The total drainage area of the river is 1704 km² out of this 1404 km² lies in Kerala and the rest 300 km² in Tamil Nadu. 
• Chalakudy river in strict geological sense is a tributary of the Periyar river.
• The river though has its origin in the Anamalai region of Tamil Nadu, is actually a collection of some major tributaries originated from Parambikulam, Kuriyarkutti, Sholayar, Karapara and Anakayam in Kerala.
• It is the one of very few rivers of Kerala with relics of riparian vegetation in substantial level. 
• It is known for its diversity, as it contains 98 species of fresh water fishes out of the 152 species known from Kerala. 
• Among these, 35 are endemic species of the Western Ghats.
• The famous waterfalls, Athirappilly Falls and Vazhachal Falls, are situated on this river.