GUWAHATI, Sept 23 � With the completion of the proposed hydroelectric power project (HEP) dams, the flow in the downstream stretch of the Subansiri river would be reduced considerably, more so during the lean period, said the Central Water Commission (CWC) in its July 5, 2013 Basin-wise Environment Impact Assessment Study on Subansiri Sub-Basin in Arunachal Pradesh (Revised Interim Report Volume-I) on the project.
The report is prepared by the IRG Systems South Asia Private Ltd (IRGSSA) with its consortium partner EQMS on behalf of the CWC.
It needs mention here that eight HEPs have been proposed on the Subansiri and of these, the 2000-MW Lower Subansiri Hydroelectric Power Project (LSHEP) is under construction at Gerukamukh on the Assam-Arunachal border.
It further maintains � �Unless the desired flow is maintained downstream of the dam, river stretches at places are subjected to near desiccation�.
In its report on the project, which was submitted to the EAC of the Union Water
Resources Ministry, the CWC said the most important changes that can be expected under the impact of the dams are � reduced flow rate, increase in water temperature, reduction in availability of stenothermal aquatic animals (that is, animals which can adapt to only small temperature range) and increase in the population of eurythermal species (that is, the species which can adapt to a large temperature range).
The report suggested provision of fish ladder in the dams of the Subansiri Hydel Power Project to save the aquatic animals like the Mahaseers (Tor tor, T putitors and Acrossocbeillus bexagonolepis).
Of the total 14494 hectares of forest area in the Upper and Lower Subansiri districts of Arunachal Pradesh, 3647 hectares will be converted to non-forest areas for setting up these projects, the report said.