It is perhaps the most unpolluted and pristine river in the state and even in India due to the limited amount of industries and wastage disposal around it.
Out of this, 26.4 hectares lie within the Vazachal area, including three large islands densely covered by riparian forests.
[10] Though officially the flood was most severe on 16 August 2018, the banks of the Chalakudy River started flooding from the early hours of 15 August 2018 due to unusually high rainfall during the monsoon season.
All the towns and villages within 5 km of the river were flooded except the slightly high hill tops.
[clarification needed] The aftermath of the flood was very severe as it changed the overall outlook of the riverway from the mountains to the river mouth.
Also the fauna in the river was greatly affected as the indigenous fish species were displaced from their natural habitats.
To make things worse, foreign species were introduced into the river system from the nearby fish farms that had hundreds of varieties of aquarium fishes like the Arapaima, Arowana, Piranha, Alligator Gar, Flowerhorn cichlid, and Red-bellied Pacu.
[11] After the floods, an Arapaima of 65 kg, which was grown in a local farm as a tourist attraction, was caught from the Chalakudy river.