‘Waste disposal turning water into poison’

 

Discharge of sewage into the Arabian sea has polluted Mumbai’s creeks and the increasing volumes of waste may take a toll on beaches and swimming areas in the sea due to the rise in the pathogen level that spreads cholera and hepatitis.
    Creeks of Versova, Mahim, Manori and Thane, along with estuaries like Ulhas, Patalganga, Kundalika, Savitri, Vashishti and the Ratnagiri Bay have become critical areas with high environmental stress.
    These are some of the observations made by experts who were part of a two-year joint study, conducted by the National Institute of Oceanography (NIO) and the Maharashtra Pollution Control Board (MPCB). Called, ‘Monitoring of Coastal Marine and Estuarine Ecology of Maharashtra’, it was recently submitted to the state.
    According to Valsa Nair-Singh, environment department secretary, the report presents observations and findings of the first phase of monitoring and survey conducted during the pre and post-monsoon of 2007-08 and highlights the current status of sea water quality and ecology of the state’s coast.
    Currently, the city receives 2,900 million litre of water daily (MLD), of which, 80% or 2,320 MLD is discharged as sewage. While Colaba has a sewage treatment plant, Worli and Bandra have marine outfalls. At Ghatkopar, Versova and Bhandup, the waste is treated through aerated lagoons.
Versova: The Versova creek showed the highest bacterial count, both in water and sediment for coastal Maharashtra. The creek system indicated deteriorated water quality such as low dissolved oxygen (DO), high nutrients and very high bacterial count, associated with organic load. It also shows the presence of metals such as chromium, zinc, cadmium, mercury and lead.
    The Versova fishing village is one of the richest in Maharashtra, with an annual turnover of Rs 100 crore through fishing activities alone, claim locals.
    At Versova, the report states, the inshore tidal water receives oxidisable organic waste (sewage) in excess of their assimilative capacity. “Though the sewage is treated through aerated lagoons before being released into the creek, the results show that either the volume released is much higher than what the creek can assimilate or the aerated lagoons mal-function,’’ reads the report. A study, which was conducted by the National Environment Engineering Research Institute in 2007 on behalf of the BMC, had claimed that the quality of water treated through the aerated lagoons before being discharged into the sea was good.
    The NIO-MPCB group also
studied the effect of sewage contamination on the flora and fauna. It found the presence of organic pollution induced phytoplankton (minute, free-floating aquatic plants) production in the creek, off Versova.
Mahim: The study found a significantly high count of pathogens, suggesting an enhanced level of contamination by sewage. Mahim creek is the seaward-end of the Mithi and the sewage and effluents from the small scale industries of Dharavi flow into it. According to the study, “The Mahim creek represented a pollution modified ecosystem showing deterioration in water quality, such as low DO, high nutrients and petroleum contamination and organic load induced high biological productivity of phytoplankton and zooplankton. The creek showed the presence of chromium, nickel, copper and lead.’’
Thane and Mumbai Harbour:
The area showed a high presence of bacteria. Terming it a new trend, the study said open sea had more bacteria count than creeks. The area receives multiple waste waters, including domestic, industrial and port based waste from Mumbai, Thane, Navi Mumbai and the Thane-Taloja-Uran-Panvel industrial belt. The results of water and sediment quality indicated that the creek system had deteriorated significantly. The open shore segments recorded high content of lead, chromium,
cadmium, mercury and zinc.
    The report has expressed concern about the high mercury contamination as it can easily be transferred to humans through the marine food chain. It has suggested that areas identified with mercury contamination must be put under regular monitoring. At Versova and Thane, it has suggested the construction of marine outfalls. “Bacterial and pathogenic contaminations both in water and sediment are alarming in selected coastal segments. Suitable measures to reduce pathogenic contamination of marine food should be considered,’’ reads the report.