Power Project in Sikkim: Potential environmental impacts

B. P. Bajgain

In Sikkim, the construction of hydro power industry is debatably one of the most resource-intensive and environmentally damaging industries for the Khangchendzonga Biosphere Reserve (KBR) as well as frail mountain sector of the Himalaya.

It is seen by the Sikkim government, as a barometer of underlying economic conditions.

When considering the potential nature conservation impacts and opportunities of the sector it is probably appropriate to recognize four main subdivisions:
• Housing

• Commercial development
• Industrial development
• Civil engineering infrastructure (such as water treatment and distribution, roads etc.).

Projects often involve the entire above benefiting public sphere such as community buildings, Roads, School and Hospitals etc.

But these projects have the potential to collision on natural habitats, affecting wildlife and plant species. The construction sector is an important user of resources, many of which are produced or derived through processes which impact on biodiversity.

The construction industry therefore has an important role to play in protecting sensitive sites and minimising damages to ecology. There are also the opportunities to enhance biodiversity by creating habitats as part of the construction or development project.

It is difficult to select between developments and damages, because the contribution of developments in long term may change tiny Himalayan state to desert carrying environmental metamorphic changes.

These issues are of key importance in some Natural Areas, especially where development pressures are most intense. These areas are Khangchendzonga Biosphere Reserve (KBR) and entire belt of River Teesta, Rangeet and some adjoining watercourse. In the name of development Sikkim is facing two type of disturbance.

1. On site disturbance

Impacts on endangered and protected species at designated site are significant.

2. Off-site impacts on habitats

These indirect effects may include pollution of air and water, hydrological impacts and disturbance. Increased risk of vandalism through vibration created by blasts and drill machines, displacement of individuals and populations of species leading to increased pressure on other sites.

Destruction of habitats:

Construction needs land and further its use can have direct impacts in terms on destruction of habitats and biodiversity such as disturbance and fragmentation. Noise and light generated during construction processes may not directly harm individual animals but it could affect feeding and breeding behaviours which could have negative impacts on long term population levels. The use of land may also divide up land and separate habitats which were previously adjacent. This can influence population dynamics especially for mobile species which rely on large habitats. The impact of fragmenting habitats on different species can be complex and can lead to gradual decline in populations which is difficult to attribute to a specific cause.

Sourcing of materials

The materials used and their processing and production will have a major impact on biodiversity. Timber, gravel, sand, iron ore, rocks etc are all major materials needed for the construction and the production of these materials can impact heavily on biodiversity.

Lack of proper planning in Sikkim:

I have gone through the Agreements and MOUs between Government of Sikkim and Power producers. State government and developers should, through good design, aiming to minimise impacts such as habitat destruction, fragmentation and species isolation, and wherever possible, should actively seek to‘re-build’ local ecological networks.

But no such effort taken in Local Biodiversity Action Plan either in MOUs and agreements and no producers adopted any interest to Avoid sites, and locations within sites, where existing key habitats, important species, buffer areas and other landscape features of major importance for wildlife.

Sector where massive construction of Hydro Power project can impact negatively:

1.         Rare Wildlife of Khangchendzonga Biosphere in Sikkim:

The selected Khangchendzonga Biosphere Reserve is a vast area and is a representative of the overall biotype of the region. As it is rich in floral wealth, the faunal wealth is also equally rich in contents. Shapi, one of the rarest fauna of this region are caprids thought to be a living fossil descended from the common ancestor of goats and antelope.

Living in the Sikkim region of Tibet and the Khangchendzonga Park, the shapi was first officially documented in 1938 by German naturalist Ernst Schaefer. It is now considered an endangered species, only 50 animals being known to exist in the wild.

List of Mammals Recorded in the Teesta Stage – V Project Area

S.No Common Name Scientific Name Local Name Area Evidence Remarks
1. Rhesus macaque Macaca mulatta Bander ES Direct
2. Assameese macaque Macaca assmenses Bander ES Direct
3. Himalayan yellow

Throated marten

Martes flavigula A V Direct Two individuals seen 2.5 km upstream from Power house site (A V)
4. Otter sp. Lutra spp. Pan oat A V Direct Secondary One individual seen 1.5 km upstream from Power house site (A V) and reported from A III, SZ
5. Tree shrew Tupaia belangeri ES Direct Seen throughout the study area
6. Flying squirrel Petaurista petaurista Rajpankhi SZ Secondary Reported from SZ
7. Jackal Canis aureus Siyal A V, A IV Indirect (scat, spoors) Regularly sighted in and around villages
8. Barking deer Muntjacus muntjac Mirga ES Indirect



Droppings seen at A II, A IV, A V and SZ, One skin seen with a local.
9. Goral Nemorhaedus goral Ghoral ES Secondary Hunted by locals for meat, skin used to make cover for locally made seats
10. Himalayan Palm Civet Paguma larvata Kala A III, A IV, A  V, A II Indirect



Sighted close to villages, Known to lift poultry
11 Porcupine Hystrix indica Dumsi A V, A I




Found on slopes and areas close to cardamom plantation
12 Asiatic black bear Selenarctos  thibetanus Bhalu SZ, A I, A II Secondary Reported to raid crop
13. Common leopard Panthera pardus Chitwa A II, A III,


Secondary Cases of livestock killing reported
14. Jungle cat Felis chaus A III Direct One individual seen on slope in mixed forest
15. Bengal fox Vulpes benghalensis SZ, A I secondary
16. Hoary bellied squirrel Callosciurus pygerythrus Lokria A II Direct Three individuals seen
17. Flying fox Pteropus giganteus A II Direct One colony of 7 individuals seen on Ficus elastica  tree

ES = Entire stretch, SZ = Submergence Zone, A I = Adit I, A II = Adit II, A III = Adit III, A IV = Adit IV, A V = Adit V (Source: report of Environment Impact Assessment Cell)

2.         Disrupt natural river flows:

By diverting water out of the river for power, dams remove water needed for healthy in-stream ecosystems. Stretches below dams may be completely de-watered. It can destroy natural seasonal flow variations that trigger natural growth and reproduction cycles in many species.

Construction of a dam can also convert river habitat into a lake-like reservoir, threatening native populations of fish and other wildlife. Dams also slow down the flow of the river. Many fish species depend on steady flows to flush them downriver early in their life and guide them upstream years later to spawn. Slow reservoir pools disorient migrating fish and significantly increase the duration of their migration. Many of the indigenous species of fish in the Teesta and Rangeet will become extinct. As per the report of Environment Impact Assessment Cell of Wildlife Institute of India, Dehradun, six among about 37 species of fishes were encountered from the river stretch passing through the Project area.

S.No Common Name Local Name Scientific Name
1. Indian longfin eel Balm Anguilia bengalensis
2. Dinnawah snow trout Chuchay Asala Schizopyge progastus
3. Alwan snow trout Dothay Asala Schizothrax richardsoni
4. Katli Katlay Acrossochellus hexagonolepis
5. Sulcatus fish Kabray Pseudechensis sulcatus
6. Annandale garra Buduna Garra annandalei

Indian longfin eel Lives in freshwaters, but also occurs in estuaries and in the sea during early life and near maturity. Dams of project may stands as hurdle for them on their migration for life.

Among the family of trout Only the Dinnawah Snowtrout is recognised as a full fledged carnivore. Pollution of water by the project lessens small water creatures.  It can lead feeding problem for Dinnawah Snowtrout. So these are the examples from the tip of iceberg.

3.         Hydropower may alter river and riverside habitat:

Constructions of a dam can results into flood at riverside lands, destroying riparian and upland habitats. Construction of a dam can also convert river habitat into a lake-like reservoir, threatening native populations of fish and other wildlife.

It is established, that combating and preserving the ecosystems is the main issue and hence individual efforts are highly essential. World Environment Day falls on June 5th every year and we just discussed on the day to forget again for another year. Isn’t its like getting a rock and hitting our own heads under the costume of celebrating World Environment Day?

Taking resolution is not enough, but putting the resolution in the proper form and acquiring the strength to end the environment problems is mandatory. This will certainly save the Khangchendzonga Biosphere Reserve and River Teesta as well as have the proper meaning of world environment day. Save own land where you stand and save the planet.

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