WATER QUALITY IN POWAI LAKE: MUMBAI, MAHARASHTRA

Sengupta, M. and Dalwani, R. (Editors). 2008 Proceedings of Taal2007: The 12th World Lake Conference: 1655-1659

Water Quality in Powai Lake: Mumbai, Maharashtra J.G. Koliyar and N.S. Rokade SIES (Nerul) College of Arts, Science and Commerce, IIEM, P -1C, Sector V, Nerul, Navi Mumbai: 400706 ; University of Mumbai, Sub-Centre Ratnagiri, P-61, MIDC, Mirjole, Ratnagiri: 415 639 Email [email protected], [email protected]

ABSTRACT This paper discusses the water quality of Powai Lake which is a large artificial lake, situated in a northern suburb of (Mumbai). Powai Lake is considered as a recreational resource. The purpose of the survey was to collect information concerning use and value of water quality improvements at Powai. This paper describes the results of a study on Powai Lake as a recreational resource. It is possible that due to presence of impurities in the lake there are many different parameters like DO, COD, Nitrogen, TDS, Conductivity, Salinity, Chloride, Total Hardness, ph, and Alkalinity was found to be increased during summer season and have got diluted during rainy season. So these kind of changes would effect the aquatic environment like increase in nitrogen content would result in eutrophication naturally which leads to decrease in the oxygen content level. Key words: Powai, Mumbai, Maharashtra

INTRODUCTION The Powai Lake of Municipal Corporation of Brihanmumbai (M.C.B.M.) is located about 27 km. away in the North-East of Mumbai City and at about 55 meters. from the mean sea level (M.S.L.). It is an artificial reservoir formed by constructing a masonry dam between two hillocks across the Powai basin in the year 1891. The watershed area of the Powai Lake is 688 hectors. The top level of the dam is 195 ft. THD, length is about 110 meters. and height is varying from 6 meters. (Max) to 3 meters. (Min). Historical Background

streams from the Eastern & North eastern slopes of hills. The authorities during the British regime intended to augment the water supply to Bombay City by creating a lake from this rivulet and in 1891 this was achieved by constructing two stone dams across two hillocks each dam was and still is about 10metres high. The spread of the water body thus achieved was about 370 acres (1.5 km²) and the depth varied from about 10 ft (off periphery) to 40 ft (12 m) at its deepest. The lake is about 17 miles (27 km) from Central Bombay. Powai Lake was built by the British at an initial cost of Rs 6.5 lakh in 1890. It was named after Framaji Kavasji Powai Estate, which was given to one Dr Scott in 1799 on payment of yearly rent of Rs 3,200. After Dr Scott’s death in 1816, Powai was taken back by the government in 1826 and leased once again to Framaji Kavasji, a Parsi merchant. At the time, Powai lake supplied two million gallons of water to Bombay. However, after Tansa Lake became a more viable option, in 1892, Powai was turned over to the picnickers Origin of Powai Lake

Figure 1. Powai Lake Powai as a location is basically famous because of the Powai lake and it is believed that the present location of Powai Lake was the original Powai Valley, a central village, with several clusters of huts each having its own well. Powai village was also served by a rivulet resulting from the rain waters of the lowest slopes of the Western Ghats, now seen as the hillock on the South end of the Lake, with

The Powai Lake is located in the heart of the suburban area of Mumbai surrounded by Vehar Lake, Powai garden, NITIE, IIT, large housing complexes, Adi Sankaracharya Marg about 2 km in length and unauthorized hutment dwellers. Geology of the Lake Mumbai formerly known as Bombay is the capital of the Indian state of Maharashtra and is the most populous Indian city with a 2005 estimated

population of about 18 million. Mumbai is located on Salsette Island off the west coast of India. Powai Lake is located about 27 km away in the North-East of Mumbai city Fig. 2. Backbay is the largest bay in the city. The coastline of Backbay is an inverted C-shaped region 4 kilometres in length, and Marine Drive is located along this stretch. North of Marine Drive is Worli Bay. In the centre of the bay is the tomb of Haji Ali, a 13th century Muslim saint. The bay perimeter is about two kilometres in length. Mahim Bay is the second largest bay in the city. The Mithi River empties into the Mahim Creek which drains into the bay. The border between the city and its suburbs bisects the bay.

Temperature The water temperature varies with the atmospheric temperature i.e. being maximum during summer i.e 35ºC and minimum during winter i.e 22ºC. pH As per pH value is concerned, it was found that throughout the month slightly lower values during monsoon season and slightly higher values during winter, but throughout the month it remained slightly alkaline. Dissolved Oxygen Dissolved Oxygen content in Powai Lake was found to be very low throughout the month. DO content ranged from 0.2 to 4.4 mg/l indicating the anaerobic conditions in the lake water. This indicates low rate of primary production in aquatic ecosystem of lake. Minimum amount required for optimum fish population may be as high as 5 to 8 mg/L. The oxygen depleting substances reduce the available DO. According to Trivedy and Goel (1986) reported that low oxygen concentrations are associated with heavy contamination by organic matter.

Figure 2. Map of Mumbai

Chemical Oxygen Demand

MATERIALS AND METHODS

Chemical Oxygen Demand test determines the oxygen required for chemical oxidation of most organic matter and oxidizable inorganic substances with the help of strong chemical oxidant. Throughout the month from April to September variations were found. The COD value ranged from 35 to 182 mg/l. As there is a variations found it indicates that some of the toxic pollutants are released to the lake water which will definitely have bad impact on the aquatic organisms found in the lake.

For the present paper on Powai lake, water samples were collected from six different sampling stations in airtight and transparent polythene containers. These six stations are located in the reservoir such as sample station ‘A’ is the water from the Dongri side of Lake, station ‘B’is water from the Centre of the Lake, station ‘C’is water from IIT side of lake , station ‘D’ is water from Sonar backbay side, station ‘E’is water from powai garden side, station ‘F’ is water from Ganpati ghat side. All samples were analysed for important physio-chemical parameters such as pH, Conductivity, dissolved oxygen, COD, TDS, Salinity, Nitrogen content. DO and pH were measured in the field with necessary precautions. The water samples were analyzed as per the proceures given in the standard methods (R.K.Trivedy and APHA) and were compared to the Stream Standards. The samples were analysed every month from April 2007 to September 2007. RESULTS AND DISCUSSION Month wise variations in physico-chemcial characteristics of Powai Lake have been studied. According to the study carried out, the status of the following parameters are observed.

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Nitrogen During the investigation nitrogen content was found to be in a varied from April to September. High levels of nitrogen in lake can be due to lack of oxygen at the bottom of the lake. Conductivity Conductivity was higher in summer months due to the increased concentration of salts which would have been caused due to evaporation during that season. The conductivity ranged from 360 to 810 Mmhos/cm. The monthly variations in the conductivity are depicted in Table 1.5.

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Powai Lake is deteriorated due to anthropogenic activities. Both Domestic sewage and Industrial effluents are responsible for deteriorating the lake environment. Domestic wastes including plastics,

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Alkalinity of the water is its capacity to neutralize acids. Alkalinity is a measure of the water ability to absorbed Hydroxyl ions without significant pH change. During the study carried out values were high during summer and low during monsoon. The reason behind steep fall of the result during monsoon may be due to dilution of water.

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Total Dissolved Solids ranged from 95 to 400 mg/l. During the present study the total dissolved solids were comparatively high in summer which decreased during rainy season due to dilution of lake water.

Graph 1 indicates DO Graph 2 indicates COD Graph 3 indicates Nitrogen Graph 4 indicates pH Graph 5 indicates Conductivity Graph 6 indicates Salinity Graph 7 indicates Chloride Graph 8 indicates Hardness Graph 9 indicates Total Dissolved Solids Graph 10 indicates Alkalinity

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The results of the parameters are explained with the help of Graph as mentioned below:-

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During present investigation the maximum total hardness (166) was found in April, it minimum (128) was recorded in September. The higher values of Total Hardness was recorded during summer and lower values during monsoon. Productive waters should have hardness value above 20mg/l. Fishes have been found to be susceptible to diseases in water with hardness below 20 mg/l. If there is increase in hardness content it becomes uncongenial for fish production because of higher pH. Optimum hardness for fish culture has been observed to be around 75 to 150 mg/l. (Das, 1996).

Due to increase in nitrogen content level eutrophication was observed in the form of weedy and other plant growth on surface of water.

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The Chloride concentrations of Powai Lake during the study were found to be below the permissible limit. Chlorides are present in water as Sodium chloride, Magnesium chloride and Calcium chloride. Although they are not harmful as such, their concentration over 250 ppm imparts a particular taste to the water rendering the water unacceptable for drinking purposes. Existence of unusually high concentration of chloride in lake indicates pollutants from domestic sewage and industrial effluents and thus leads to eutrophication. In addition to that salinity was also calculated which too shows increase in during summer season and decrease in monsoon season. It was originally conceived as a measure of the mass dissolved salts in the water samples.The salinity content ranged from 542 to 1066.

religious floral wastes as well as immersions of idols are done in the lake which leads to damage the lake environment.

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CONCLUSION It is possible that due to coassive presence of impurities in the lake there are many different parameters found to be increased during summer season and have got diluted during rainy season. So this kind of changes would affect the aquatic environment like increase in nitrogen content would result in eutrophication naturally which leads to decrease in the oxygen content level. Lack of oxygen content can cause fish kills and lack of fish enables malaria-hosting mosquitoes as mosquitoes are natural food for fish. Without oxygen at the bottom at all times beneficial bacteria and insects cannot biodegrade the organic sediment at bed level of the lake. All these could lead to large accumulation of sediments at the bottom. All parameters would be analysed after a interval of period so as to maintain the lake. Powai Lake was declared as “National Lake” where various steps were adopted for the development of the lake. Bathing, washing and defecation were strictly prohibited. Ganesh idols were immersed during Ganapathi festival which has also deteriorated the lake water by increasing certain parameters which is indirectly affecting the aquatic organisms found in the lake. A strong attempt should be made in order to save the lake environment. Throwing waste materials and garbage in the lake water should be strictly prohibited. Purification methods should exist from filtration processes that should be carried out before introducing any foreign material in the water body. The above results itself gives clear idea that some pollutants are released in the lake. Proper Bioremediation techniques should also used in order to improve the water quality. Regular EIA on Powai Lake should be carried out and different changes should be observed. Regular maintenance steps must be carried out for a certain period to observe its advantages and its respective quality.

Chandrashekhar, S.V.A. 1996. Ecological studies on Saroornagar lake, Hyderabad Ph.D. Thesis. Osmania University, Hyderabad. Pant,M.C.a and A.P. Sharma and P.K. Gupta. 1979. Trophic Status of two lakes of Kumaun. Proc. Symp. Environ. Biol. Academy of Environmental Biology, 203-209. State of Environment Report for Maharashtra by Maharashtra Pollution Control Board, 2007. Mani Bharat abnd S.A.Gaikwad. 1998. Physico-chemical Characteristics of lake Pokhra. Indian J. Environ and Toxicol, 8(2): 56-58. Kodarkar, M.S., D.D. Diwan, N. Murugan, K. M. Kulkarni and Anuradha Ramesh, 1998. Methodology for water analysis (Physico-chemcial, Bilogical and Microbiological). Indian Asso. Of Aqua. Biologists, Hyderabad. Pp 102.

REFERENCES APHA-AWWA-WEF. 1998. Standard methods for the examinations of water and waste water. 20th ed. APHA, Washington D.C. Trivedi, R.K. and Goel, P.K. 1986. Chemical and Biological Methods for Water Pollution Studies (R.K. Trivedi and P.K. Goel ed. ) Environmental Publications, Karad, India. Badve, R.M.., K.P.N. Kumaran and Rajshekhar C. 1993. Eutrophication of Lonar Lake, Maharashtra. Current Sci, 65(4): 347-350. Md. Babar and P.S. Wakte (Geoenvironmental and Microecological Characteristics of Lonar Lake, Maharashtra). Ecology of Lakes and Reservoirs Pg 111-124. 2006. Singh, D.N. 2000. Evaluation of physico-chemical parameters in an oxbow lake. Geobios, 27: 120-124.

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