The Palaruvi waterfalls near Aryankavu in Kollam district will remain closed to visitors from Saturday until further notice.
The closure is the result of the waterfall going almost dry following drought conditions in the area, the Forest Department said.
The drought conditions were forcing wild animals to the area of the waterfall in search of water.
The presence of people would disturb the animals. Moreover, the lack of water was proving to be a let-down for visitors.
The waterfall is located inside the forests under the Aryankavu Forest Range.
Last week, a group of young men vented their ire at the lack of water by heaping up dry leaves and setting them on fire.
They then disappeared. Alert Forest personnel and volunteers of the Vana Samrakshana Samithi noticed the fire and put it out.
It is feared that similar incidents could recur.
The closure is likely to be in force till the onset of the monsoon in June, a Forest 0official said.