North-east India, represents the confluence zone between the Indian, Indo-Malayan and Indo-Chinese biogeographical regions. The North-east zone is therefore the "biogeographical gateway" for much of India's fauna and flora, and as a consequences, one of the richest in biological values. The state of Assam is the largest part of zone - 8 representing the North-east India (Rodgers & Panwar, 1988). Of all zones of India, it is perhaps the richest in communities, in species and in endemism.

The variety of flood pains of Brahmputra river and the forested hills with a mixture of swampy grasslands, evergreen deciduous and sub-tropical forests are floristically extremely rich and also contain significant primate, carnivore and bird communities. Elephants (Elephas maximus), Rhiniceros Rhiniceros unicornis), Wild Buffalo (Bbbalus bubalis), Swamp Deer (Cervus duvuaceli), Hog-Deer (Axis porcinus), Pygmy Hog (Sus salvanius), and Hispid Hare (Caprolagus hispidas) represent the herbivore fauna of the swamp grassland communites. North-east contains 10 of the 15 known species of primates (Choudhaury, 1989). Some of the very rare rpimates like the pig tailed (Macaca nemestrina) and Stump-tailed Macaque (Macaca arctoides), and Hoolock Gibbon (Hylobates hoolock) are charecteristic of the forested area of this zone. The state also offers a home to a wide variety of birds particularly the pheasnts and hornbills.

It has been observed in the recent years, that the basic ecological format of the state is changing due to multifaceted impacts of various developmental projects that are essential part of modernization and industrialization in the state (Bhattacharjee, 1996). The number of forest based industries in the state of Assam is fairly significant. There are about 52 plywood mills, currently operating. River valley projects have also exerted tremendous pressure on the natural habitat of Assam. The projects like Borapani Hydro Electric Power (HEP), Dhansari Hydel Scheme and Puthjamri project are some of the proposed projects that are likely to result in the decimation of areas under wildlife habitats. Taking forest cover alone as a simple index of habitat loss, one can predict the adverse effect of this loss, on animal population. According to the assessment of the forest cover of the country on a two year cycle conducted by Forest Survey of India, the forest cover of the north eastern states are declining at the rate of 0.5 percent (FSI, 200) which is much higher than the national average (0.2 percent) per two year.

In such a precarious situation, it becomes all the more crucial to make a careful assessment o the possible implications of all the developments, whether big or small in different sectors. Environmental Impact Assessment of any proposed developmental project not only provides an adequate understanding of the likely environmental impacts but also provides the scientific basis for evolving mitigatory strategies and environmental safeguards wherever possible.