Powai lake

POWAI LAKE

Powai Lake (named after Framaji Kavasji Powai Estate) is an artificial lake, situated in the northern suburb of Mumbai, in the Powai valley, where a Powai village with cluster of huts existed. The city suburb called Powai, shares its name with the lake. Indian Institute of Technology, Bombay one of the premier institutions of science and technology in India is located to the east of the lake.[1] Another famous institution, the National Institute of Industrial Engineering (NITIE) is also located close to the lake. Housing complexes and plush hotels are developed all around the lake periphery. Population around the lake has thus substantially increased over the years.

When it was built, the lake had a water spread area of about 2.1 square kilometres (520 acres) and the depth varied from about 3 metres (9.8 ft) (at the periphery) to 12 metres (39 ft) at its deepest.

The Powai Lake has gone through many stages of water quality degradation. The lake water which used to supply to Mumbai for drinking water has been declared unfit to drink. The Lake still remains a tourist attraction

The Powai Lake has gone through many stages of water quality degradation. The lake water which used to supply to Mumbai for drinking water has been declared unfit to drink. The Powai

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Lake has gone through many stages of water quality degradation. The lake water which used to supply to Mumbai for drinking water has been declared unfit to drink. The Lake still remains a tourist attraction.

HISTORY

A stream tributary of Mithi river, which served the Powai village's water supply needs, was dammed in 1891, during the British period, initially to augment water supply to the then Bombay city (now called Mumbai), by constructing two dams of 10 m height each to store the rain waters flowing from the lower slopes of the Western Ghats and streams from the eastern and northeastern slopes of hills.[4] It was planned as an antiwater famine measure, to the southeast of Vihar Lake (a much larger lake) also for water supply to Mumbai city.

Before the lake was built by the British, in the year 1799 A.D., the estate where the lake is now located was leased on a yearly rent to Dr. Scott and after his death in 1816 A.D., the government took control of the estate in 1826 A.D., and leased it once again to one Mr. Framaji Kavasji, a Parsi merchant, after whom the lake was named when it was built in 1891.

The drinking water supply objective of the lake was abandoned in the early 1990s, in view of poor quality of the water stored, caused due to pollution, water hyacinth and weeds, untreated


sewage and large silt deposit. The lake was, therefore, leased out to the Western India Fishing Association, a quasi government organisation who used it for both fish culture and angling. Later, the Bombay Presidency Angling Association was formed in 1936 and later in 1955, under the Societies Registration Act 1860, it was registered as “The Maharashtra State Angling Association” (MSAA) and the lake is now under their control. Realising the gravity of the environmental pollution of the lake, the MSAA has revised its constitution,

to actively care for, clean, develop, maintain, and beautify the Environment at Powai Lake.

MSAA is now involved with a) removal of water Hyacinth infestation, b) supporting research with Fisheries Dept.for conservation of the Indian Mahaseer, c) Water quality analysis d) and augmenting security.

ACCESS

The lake is about 40 kilometres (25 mi) from Mumbai by road and is approached via King's Circle, Sion, and Kurla or through Santa Cruz and Andheri.[6] Kanjurmarg on the central main line of the Mumbai Suburban Railway is the nearest railway station to the lake.

HYDROLOGY AND WATER QUALITY


It is reported that the average rainfall at Powai is about 2,540 centimetres (1,000 in), and the lake overflows for about for sixty days each year. The overflow from the lake flows into the Mithi River. Silt studies conducted in 1995 estimates that 4500 lakh cubic metres of silt has been deposited in the lake since its construction.[2] It supplied two million gallons of water to Bombay (now Mumbai) when it was built. Following the construction of the Tansa dam and creation of the reservoir, in 1892, Powai waters were used for irrigation.[7] The lake drains a catchment of 6.61 km2 (part of the Powai-Kanheri hill ranges which also drain into the adjoining Vihar Lake and Tulsi Lake). The dam, built in stone masonry has a height varying from 3 m to 6m with top level of the dam kept at E.L. 58.5 m (with Town hall datum).[8] Government of Maharashtra reports that due to eutrophication of the lake water from untreated sewage and garbage from nearby residential and slum colonies, the lake


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water is unfit for drinking water use. Hence, the lake is now used for recreation, gardening, cattle washing and fishing. The water of the lake is also supplied to Aarey colony and L&T for non domestic uses. Dissolved Oxygen (DO) level at the bottom of the lake is reported to be 0.71 mg/litre and at surface 4.11 mg/litre, average value of pH is 7.2 and COD is 42.70 mg/litre on the surface and 119 mg/litre at the bottom of the lake.

LAKE REJUVENATION

Appreciating the problem of silting, growth of water hyacinth, weed, and eutrophication of the lake, the IIT Bombay's Class of 1980 launched a "Revitalization of Powai Lake” with the objective of restoring the lake to its original pristine and sustainable form by adopting Eco-friendly designs and materials for the restoration works.

Some of the tasks proposed to be undertaken with the funds donated by IIT, Bombay included:

• Removing water hyacinth and weeds from the lake in parts nearest to the campus

• Starting a publicity and an awareness program in the area

• Building embankments, walkways and pathways to the lake

• Constructing a large gazebo for an evening (or morning or afternoon) by the lake


• Planting trees, and creating a garden

• Installing docks, deploying boats and canoes

• Allocating funds for annual maintenance

The project was proposed to be professionally managed with a project manager working under directives of IIT Bombay with an “Oversight Committee“ to monitor objectives set for the restoration work.

In 1995, the National Lake Conservation Plan (NLCP) of the Ministry of Environment and Forests (MoE&F),Government of India, reviewed the condition of Powai Lake and included the Lake in its list of ten major lakes in the country for revival and improvements. The restoration/revival programme, fully funded by the NLCP, was launched in April 2002, and implemented by Bombay Municipal Corporation (BMC) now called Brihanmumbai Municipal Corporation (BMC), the Government of Maharashtra and as a result the status of the lake has undergone a major shift from the hypertrophic condition to mesotrophic condition by adopting a novel technique of aeration and bioremediation. This has resulted in the lake being used for fishing and recreational purposes.

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 mo nth 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 (1 986) reported that low oxygen concentrations are associated with heavy contamination by organic matter.

Nitrogen

During the investigation nitrogen content was found to be varied from april to September.High level 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 concen tration of salts which would have been caused due to evaporation during that season. The conductivity ranged from 360 to 810 Mmhos/cm.

Chloride

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.

MAJOR CAUSES OF DETERIORATION OF LAKEo Uncontrolled development and unauthorized

quarrying activities in the catchments area.

o Ingress of untreated sewage from the residential areas.


o Dumping of garbage and other waste materials in the lake.

o Washing of clothes, vehicles, open defecation etc. On the lakeshore.

DESILTING PROJECT

The Lake's water depth is reported to have reduced to as little as 0.33 metres (1.1 ft) at some locations, on account of the large inflow of sewage, domestic waste water and silt from surrounding residential and industrial areas.

Brihanmumbai Municipal Corporation (BMC) has therefore plans to desilt the Powai Lake at a cost of US $9 million.

FAUNA


Large number of crocodiles on the lake side have been sighted on the shores of the lake and also reported by fishermen and officials of IIT, Powai.

White throated kingfisher, small blue kingfisher, spot-billed duck, spotted dove, a few purple moorhens, purple rumped sunbirds, bronze winged and phaesant tailed jacanas, ashy prinias, brahmany kite, Red vented, red whiskered and white browed bulbuls, cormorants, lesser whistling ducks, grey, purple and pond herons, little,


intermediate and large egrets,, perigrine falcon, greater coucal, rose ringed and Alexindrine parakits, Eurasian marsh harrier (possibly winter visitor), wooly necked stork (winter visitor) hopooe & whiskered terns. butterflies, honey bees, bumble bees and beetles have also been sighted.

FLORA

Balsam bushes, in their full bloom, in pink-purple color are seen around the lake periphery, like a carpet.

Powai Lake is an artificial lake, situated in the northern suburb of Mumbai. The lake was created in 1891 by constructing dam between two hillocks across Mithi River. Catchment area of the lake is about 600 hectors and water spread area at full supply level is 220 hectors. The lake water is used for non-potable purposes i.e. gardening and industrial use.


In recent times, 40% of the lake has disappeared. The lake has deteriorated due to accelerated growth of residential,

commercial and industrial area around the lake. The untreated disposal of sewage and garbage from nearby residential and slum colonies have affected the quality of the water.

Dissolved Oxygen level at the bottom of lake has gone low as 0.71 mg/ltr, and at the top it is 4.11mg/Ltr. The catchment of the lake has also been affected badly due to unplanned

quarrying activities.

Appreciating the problem of silting, growth of water hyacinth, weed, and eutrophication of the lake, the IIT Bombay's Class of


1980 launched a "Revitalization of Powai Lake” with the objective of restoring the lake to its original pristine and sustainable form by adopting Eco-friendly designs and materials for the restoration works. In 1995, the National Lake Conservation Plan (NLCP) of the Ministry of Environment and Forests (MoE&F), reviewed the condition of Powai Lake and included the lake in its list of ten major lakes in the country for revival and improvements. The restoration/revival programme, fully funded by the NLCP, was launched in April 2002, and implemented by Bombay Municipal Corporation (BMC) now called Brihanmumbai Municipal Corporation (BMC).

Adjoining Attractions Mahakali Caves

The Mahakali caves built about 2000 years ago has several rock-cut figures of the Buddha and Buddhist legends. These caves are situated in Udayagiri hills near the Kondivita village.

Kanheri caves

The Kanheri Caves are located north of Borivli on the western outskirts of Mumbai, within the Sanjay Gandhi National Park's green forests.

Sanjay Gandhi National Park wildlife park


Sanjay Gandhi National Park, earlier called Krishnagiri National Park covers an area of 104 sq. km and is the largest park in the world, located within city limits.

CONCLUSION Powai lake having catchment area of 6.61 Sq. Kms &

lake surface area of 2.10 Sq. Kms is improved within a period of 12 months. This is the 1st successful project executed in India using “Aeration and Bio-remediation Technique”.

The status of lake was transformed from Hypertrophic condition to Mesotrophic condition.

Use of the aeration and bioremediation technique was effective for improving the quality of lake water to the accepted standard for water bodies being used for fishing and recreational purposes.

Though the installation cost of equipment, power and monitoring the water quality is high, the cost of maintenance is relatively low.



Education

Powai lake