The Pampa breached its banks at Pampa-Triveni in the foothills of Sabarimala flooding the Pampa Manalpuram on Thursday morning.
The floodwaters entered the Annadana Mandapam of the Travancore Devaswom Board as well as shops and hotels on the banks.
The police and Akhila Bharata Ayyappa Seva Sanghom helped the pilgrims returning from Sabarimala after the Niraputhari celebrations at the Ayyappa temple to safely cross the river.
There is heavy rain in the forest areas of Sabarimala since Wednesday afternoon.
Minor landslips
The tribals at the Attathode settlement, near Nikackal, suspect a series of minor landslips in the forest interiors might have caused the flash flood at Pampa-Triveni on Thursday morning.
With the rain subsiding, the floodwaters started receding from Triveni and surrounding areas by 11.30 a.m.
A section of the plastic sand bags stacked on the western bank of the river too caved-in in the floodwaters.
However, no damage to property was reported from Pampa till afternoon.
The causeway leading to the Kurambanmoozhy settlement colony in Ranni too was under water on Thursday forenoon.