Ulhas River

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The Ulhas River is a west-flowing river in Maharashtra, India. It is in the Thane, Raigad, and Pune districts of that state. The Ulhas River is approximately 122 kilometres long. Its basin covers a densely populated and industrialized region, making it one of the most significant river systems in the Mumbai Metropolitan Region (MMR).

It flows north and west from it source to where it splits into Vasai Creek and Thane Creek, near Thane. The Ulhas divides Salsette Island from the mainland, and is important for the water supply of Mumbai.^[1]^[2]^[3] It originates near the Tungarli Lake in Lonavala, flows northwards through Karjat until it merges with the Poshir River at Nikhop. Further north, it merges with the Barvi River near Vasant Village. The largest tributary, Kalu River joins in the Ulhas north of Godrej Hill, Kalyan. The volume of the water is increased significantly. Finally at Thane, it divides into two streams, one goes towards Vasai into the Arabian Sea and the other south into the Thane Creek. It flows through cities like Karjat, Dombivli, Kalyan, and Thane.

The river is one of the major cause behind the floods observed in Mumbai each year during the monsoon season. Particularly, during the 2005 Mumbai floods the Ulhas River overflowed following unprecedented rainfall, severely affecting the Kalyan–Dombivli region.

The Ulhas River has been an essential water source for centuries. It has supported agriculture, trade, and settlements along its banks. The river has a rich history, with its waters used extensively during the British colonial period for transporting goods. It continues to be vital for irrigation and domestic water supply in the Thane region.

Throughout the years, however, the rapid urbanisation and industrialisation in the Mumbai Metropolitan region has changed the face of the river and wreaked havoc on the lives, humans and fauna, dependent on it. ^[4]