Unfortunately I cannot find this book at Goodreads yet, but the Hindu Business Line has an interesting article with the title:

Unquiet Flows a River: The English translation of a famed 1974 Tamil novel lets a broader audience take in the ethos of a subaltern people in a fecund Dravidian belt

Amazon has a short description up:

On a River’s Bank is a story of ordinary people through an extraordinary narrative. In what must be a rare and sensitive portrayal of an ugly female character, the author underlines that violation of the river leaves it ugly and invites retribution despite worship. Published originally in 1974 in Tamil, Punalum Manalum is a path-breaking novel raising the issue of environmental degradation through over-exploitation, long before this became a topic of discussion in India. An early example of what is now known as ‘Eco fiction’.

The translation was published in May 2018. I’ll be watching for any updates.

The article at HBL says:

The novel, for all its care for the ‘lowly’ characters, brims with the descriptions of the vibrantly rich flora and fauna of the riparian region. Its endemic birds, animals, plants, flowers and trees besides the changing hues of the sky and the moods of the sun come in opportune times. Often, they add to the mood and conduct of the human beings under a benign local god called Madan Sami, in whose name an annual festival is a big celebration on the banks. Yet, it is the river that occupies a special place: several situations and actions are expressed by uncannily bringing in river-related images. Loneliness, for instance, is like a “river at night”. A cobra and a krait, fighting ferociously, make movements “like whirling current of water”. Thoughts with clarity are like “goldfish swimming”. A fatigue-hit Angusami is like a boat with a hole in the bottom. Such changes are normal: “Even the clear river water turns muddy when it rains.”