"It has rained heavily in the district over the past two days and the Bhagirathi river is flowing just two metres down the danger mark at 1102 metres. So an alert has been sounded and authorities have been asked to keep a watch," Uttarkashi District Magistrate Shridhar Babu Addanki told PTI on phone.
Tiloth, Purikher and Valmiki basti have been identified as the three vulnerable areas where a special vigil is being maintained, he said.
"The alert is a precautionary measure as we don't want to take any chances with last year's catastrophic flash floods in the backdrop," he said.
Uttarkashi was one of the most badly affected districts in Uttarakhand apart from Rudraprayag and Chamoli districts in last year's deluge.