When it was built, the lake had a water spread area of about 2.1 sq.km (370 acres) and the depth varied from about 3 m (10 ft) (at the periphery) to 12 m (40 ft) at its deepest..
The Powai Lake has gone through many stages of water quality degradation. The lake water which used to be supplied to Mumbai for drinking water has been declared unfit to drink. The Lake still remains a tourist attraction..
A stream, tributary of Mithi river, which served the Powai village of its 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 & North eastern slopes of hills.. It was planned as an antiwater famine measure, to the south east 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 1990's, 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 environment pollution of the lake, the MSSA has revised its constituion,
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.
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.
Brihanmumbai Municipal Corporation (BMC) has therefore plans to desilt the Powai Lake at a cost of US $ 9 million.