On Sunday, 7 February, a sudden, exponential rise in water level in Rishiganga River near Reni village, Chamoli district, led to a catastrophic flood downstream. This damaged the 13.2 MW RishiGanga power project, some bridges, Reni village, the 530 MW NTPC Tapovan hydro-power project downstream on the river Dhauliganga, as also the Joshimath-Malari Highway. Eighteen bodies have been recovered at the time of writing this article, while over 150 persons are still missing. Had the river channels been full with snow-melt waters, as in summer, the devastation would have extended further downstream.
Experts are still uncertain as to what actually triggered this rapid rise in water in the Rishiganga River, a tributary of the Dhauliganga. Some reports suggest that a large avalanche near the terminus of Nanda Devi glacier caused a flash-flood in the Rishiganga. Others maintain it was a Glacial Lake Outburst Flood (GLOF).

