Objective

The Municipal Corporation of Greater Mumbai (MCGM) has proposed to develop additional source of drinking water supply due to increasing demand of water requirement for the megapolis of Mumbai. The project envisages the development of impoundage through construction of Middle Vaitarna dam to provide 455 MLD of water supply to the city. The raw water conveyance system is proposed from Modak Sagar (Lower Vaitarna dam) through a 7.5 km long tunnel of 3.5 m dia. upto Bel-nalla followed by 3.0 m dia. MS pipeline parallel to the existing pipelines in three parts on municipal land transporting raw water to proposed new Bhandup water treatment plant. The MCGM will execute the various components of this IV Mumbai Water Supply Project.

As a result of construction of Middle Vaitarna Dam, approximately 630 ha area of forest will come under submergence. In order to estimate the loss of biodiversity caused due to submergence, it was felt necessary to conduct the study, so that ecosystem restoration programme as per MoEF guidelines can be initiated by the sponsor.

Scope

• Evaluation of major vegetation in submergence area following quadrant method

• Application of diversity indices with reference to importance value index (IVI) of the
  area

• Ranking the varieties of trees starting from most important to least important species

Summary

The major environment components studied during the survey of submergence area at MVD in March 2007 is land and biological environment. The terrestrial component in the proposed Middle Vaitarna dam project indicates that there will not be any

appreciable changes as envisaged in the earlier reports on (A) EIA report of Middle Vaitarna Dam (B) Enumeration of trees for IV Mumbai (Middle Vaitarna) water supply project and (C) Catchment Area Treatment Plan. The review of all the reports for protecting the environment due to project activities, the present situation at the project site, the financial allocation for preservation of environment reveals that the project may be taken up for implementation. The environmental management plan suggested in the comprehensive EIA report and the requirements of forest department may scrupulously be followed to maximize the overall benefits apart from additional water supply need for the mega city of Mumbai.