(a) whether construction of dams and hydro power generation projects cause water pollution;
(b) if so, the nature of such pollution;
(c) whether any scientific survey has been conducted in this regard;
(d) if so, the details indicating the opinion of the Government thereon;
(e) whether any report of similar kind outside India have come to the notice of the Government; and
(f) if so, the details thereof?
MINISTER OF ENVIRONMENT AND FORESTS (SHRI T. R. BAALU)
(a) & (b) Impoundment of water resulting from construction of dam and hydropower generation may result in decrease in dissolved oxygen (DO) levels and build-up in levels of dissolved carbon dioxide (CO2) as a result of impoundment.
(c) & (d) The Himachal Pradesh State Environment Protection and Pollution Control Board has studied water quality in three reservoirs, namely – Bhakhra reservoir, Pong reservoir and Pandoh dam . The study has shown that depletion in dissolved oxygen(DO) and increase in Bio-chemical oxygen demand(BOD) content is more rapid in the case of depth profiles than the longitudinal profiles. Further, it has also been seen that BOD increases towards the reservoirs both on longitudinal and depth profiles
(e) & (f) In this regard, studies have also been carried out on dams in USA and Canada. The findings depend on locational aspects and no general conclusions could be drawn.