Vihar Lake is a critical man-made reservoir serving as one of the seven primary water sources for the city of Mumbai. Located on the Mithi River within the Sanjay Gandhi National Park, it was constructed by the British between 1856 and 1860. The lake's overflow is a significant annual event monitored by the Brihanmumbai Municipal Corporation to manage the city's water supply levels. It is integrated into a system of reservoirs that includes Tulsi and Powai lakes.