Its source is in a place by the same name 'Cooum' or 'Koovam' in Tiruvallur district adjoining Chennai district. Owing to intensive use of surface water upstream for agriculture, indiscriminate pumping of groundwater leading to reduced base flow in the river, formation of sand bar at the mouth of the river, discharge of untreated sewage and industrial effluents and encroachment along the banks, the river, especially the downstream, has been highly polluted.