The 450-km long Subarnarekha with a basin area of 1.9 mha is the smallest of the 14 major rivers in India. It flows through the mineral-rich industrial belt of Jharkhand, West Bengal and Orissa.
The river has been increasingly polluted over the last few decades due to increasing mining activity, industrialization, urbanisation and deforestation in the upper and middle reaches of the river basin. Between JadugodaandBaharagora(and further downstream), the river is contaminated with radioactive materials due to the mining and processing of the uranium.
The arc-shaped Singhbhum copper belt is a major source of river pollution. There are four industrial areas (Ranchi-Hatia, Muri. Adityapur-Tatanagar, Jadugoda-Ghatsila) which contribute maximum pollution load of the river. The daily organic pollution load generated in the Subarnarekha basin stands at 264 tons from rural and urban sources. Out of 117 tons of total BOD load two-thirds are generated from Ranchi and Singhbhum districts of Jharkhand.
Industrial units also throw COD load, suspended solids, oil and grease, phenol, fluoride and nitrates to the river. The Upper segment from Hatia dam to Baharagora is polluted by uncontrolled discharge of untreated or semi-treated domestic waste effluents. Runoff from agricultural lands transports 450 tons of nitrogen. 120 tons each of phosphorus and potassium along with small quantity of organ chlorine pesticides to the river annually.
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While the water quality of the river has been officially classified as grade C’, downstream from Jadugoda it cannot be above grade D. The cleaning programme of the Subarnarekha has been undertaken by the National River Conservation Plan (NRCP). Accoridngly domestic effluents from Jamshedpur, Ranchi and Ghatsila urban centers will be treated before their disposal to the river.