Teesta - Ministry of Power

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Preliminary Feasibility Report
Teesta (I) HE Project (4 x 80 MW)
river, which flows through the states of Sikkim and West Bengal in Indian Territory
and then to Bangladesh. The river rises in mountainous terrain and is formed mainly
by the union of two hill streams Lachen Chu and Lachung Chu at Chunthang in North
Sikkim. The river upto this reach generally flows in a very steep gradient and the slope
of the Teesta river upto the confluence of Lachen chu and Lachung chu is about 1 in
20. After the confluence of Lachen chu and Lachung chu at Chungthang the river
gradually increases in width and takes a wide loop flowing down to Singhik dropping
in elevation from EL 1550 m to EL 750 m. It is here after traversing about 20 Km that
the river confluences with Tolung Chu.
The area has a rugged terrain with the surrounding peaks reaching a maximum
elevation of approximately 4000m. The minimum river bed elevation at both the
proposed dam sites is about 3230m. The terrain hosts a rich growth of vegetation. In
general the river flows in southeasterly direction. Numerous valleys are seen in the
area, which are occupied by cultivated terraces. Few high level terraces have been
observed in this area especially in vicinity of Lingza and Kayem village.
5.2.1 Cascade Development In Teesta Basin
The river Teesta has tremendous potential for development of hydro power, as the
river descends from an elevation of about 3600m to about 300m over a distance of
about 175 Km. According to the preliminary reconnaissance survey by Central water
and power Commission in 1974, the river could be harnessed under a cascade
development for hydro power generation. The cascade development proposed at that
stage consisted of power generation in six stages on river Teesta. Out of these
schemes, NHPC had submitted a DPR for Teesta H.E project, Stage-III in 1990. The
diversion structure for Teesta-III was proposed to be constructed at Chungthang,
which lies downstream of the confluence of Lachen Chu and Lachung Chu. Another
project under Teesta Basin development, which is under execution by NHPC, is
Teesta Stage-V having an installed capacity of 510 MW, where a diversion structure is