Mumbai’s most expensive real estate areas are surrounded by high levels of water pollution, a study by the state pollution control board has said.
A pollutant-measuring indicator – water quality index (WQI) – of sea surface water at Malabar Hill, Nariman Point, Gateway of India, Worli sea face, Juhu and towards the Bandra end of the Mithi River showed high pollution as a result of a surge in domestic waste being deposited in these areas. The study was made public on Friday.
Between March and August 2016, the Maharashtra Pollution Control Board (MPCB) carried out water quality monitoring, under the National Water Monitoring Programme of the Union environment ministry, at 188 locations in the state. There were four parameters – pH, dissolved oxygen, biochemical oxygen demand and fecal coliform – to calculate WQI for surface water. WQI is represented in colour bands.
As per the National Sanitation Foundation, USA, that developed WQI – a standardised method to compare water quality of various water bodies, a WQI reading between 63 and 100 is in the ‘good to excellent’ category denoted by the colour green, 50-63 is ‘medium to good’ (yellow), 38-50 is recorded as ‘bad’ (orange), and 38 and below is identified as ‘bad to very bad’ (red).
- Sea surface water at:
- · Malabar Hill, Walkeshwar
- · Nariman Point, Colaba
- · Gateway of India, Colaba
- · Worli sea face, Worli
- · Juhu, Juhugaon
- · Towards the Bandra end of the Mithi River
“We had been accumulating data since 2004. However, we decided to come out with a precise number to identify water quality to the public through this study. The idea is to introduce WQI for awareness purposes for local municipal corporations or other bodies to take stock of pollution levels at nearby water bodies,” said a senior official from MPCB’s water quality department.
Of the 188 locations, the study observed 164 or 87.3% locations fell under the categories of ‘good to excellent’ (112 sites) and ‘medium to good’ (52 sites). WQI figures for 16 locations fell under the ‘bad’ category --- which included the six locations from Mumbai, six locations from Pune and four from Raigad and Thane. Eight remaining locations in Raigad, Thane and Palghar were identified to have the worst water quality under the ‘bad to very bad’ category.
- · Kunalika River, Arekhurd, Raigad
- · Rabodi Nullah, Thane
- · Colour Chem Nullah, Thane
- · Tarapur MIDC Nullah, Palghar
MPCB officials said 80% of the pollution source for Mumbai, Pune, Thane and Raigad was untreated domestic waste. “We observed that the coastline along megacities like Mumbai and rivers and lakes in smaller cities had an inflow of sewage that is being channeled through nullahs to the water bodies,” said the official. “The remaining 20% pollutant source consisted of a small quantity of oil, industrial effluents and rest was natural sources arising from the base of water bodies.”
The official said meetings had already being held with 37 local bodies across the state to treat their sewage at source. “While Mumbai still has a good sewage treatment facility, other cities need to ensure they treat their sewage through MPCB approved treatment facilities,” he said. “Awareness drives have been conducted and directives have been issued to municipal corporations. We expect that the index will change towards the fairer side through a similar study within a year or two.”
What is WQI?
A water quality index provides a single number (grade) that expresses overall water quality of a certain water sample (location and time specific) for several water quality parameters. A water index is based on important parameters, which provides a simple indicator of water quality and a general idea on the possible problems with the water at a particular region.
Interpretation of Water Quality Index – Surface Water
Class (as per Central Pollution Control Board)
Good to Excellent
Medium to Good
|38 and less||Bad to Very Bad||D, E||Heavily Polluted||Red|
(Source: Maharashtra Pollution Control Board’s state water quality assessment under National Water Monitoring Programme)