The river collects surplus water from about 200 tanks and lakes, small streams and the rainwater drains in the city, with a combined catchment area of 860 square kilometres (331 sq mi).

[1] The Adyar starts from the Malaipattu tank (80.00° longitude and 12.93° latitude) near Manimangalam in Sriperumbudur taluk at about 15 kilometres (9 mi) west of Tambaram in south Chennai.

It begins to resemble a stream only from the point where water released from Chembarambakkam Lake joins the river at Thiruneermalai.

[2][3] Here it forms an estuary, which extends from Adyar Bridge to the sandbar at the edge of the sea, with some small islets in between.

However, with the city's sewage and effluence from its various industries, for some time, emptying into the river, the biological activities in the region was affected.

A few years before, the Theosophical Society has come out with a CD on 'Birds of Adyar', compiled by the Trust for Environment Monitoring and Action Initiation.

Efforts were being made by the AIADMK government to close sewage inlets, free the flood banks from encroachments, and replant native varieties of trees after cordoning of the river, to prevent further illegal occupation since the Chennai Floods of 2015 and have been reasonably successful.

The Theosophical Society, Anna University, Madras Boat Club, Thenral are prominent institutions located in the banks of Adyar.

Bridge is nearly 480 metres (1,570 ft) that enabled tidal effect into the waterway for about 4 kilometres (2.5 mi).

However, it was essential to provide groynes to keep the river mouth open for adequate width and prevent inundation during monsoon.

In 2011, the Water Resources Department (WRD) proposed to construct groynes to reduce formation of sand bars near the mouth the river.

[10] In 2012, the state government allotted ₹ 3,000 million towards construction of 337 sewage cleaning systems in the waterways in the city, including 49 locations in the Adyar river.

However, ever since the devastating Chennai Floods of 2015, where 29,000 cusecs of water were estimated to have been released, purging everything in its path, the present AIADMK government, has made sustained efforts, to clean the river, with reasonable success - including cordon of its bank with a dedicated wall, remove encroachments from the Jaffarkhanpet End, till the mouth of the river near the Broken Bridge, along its flood banks, as well as regularly de-silt its sister channels, stormwater inlets and the river itself.