“The water level of the river is now one metre (3.2ft) above normal but the flow is decreasing,” Mr Singh Rawat said.
The neighbouring state of Uttar Pradesh has put some riverside areas on high alert for flooding.
Experts are investigating the incident.
What caused the glacial burst?
The remoteness of where this happened means no one has a definitive answer, so far.
Experts say one possibility is that massive ice blocks broke off the glacier due to a temperature rise, releasing a huge amount of water.
And that could have caused avalanches bringing down rocks and mud.
“This is a strong possibility because there was a huge amount of sediment flowing down,” said DP Dobhal, a senior glaciologist who just retired from the government’s Wadia Institute of Himalayan Geology.
Experts say an avalanche could also have hit a glacial lake that then burst out, if there was any such water body there.
Another possibility is that an avalanche or landslide may have dammed the river for some time, causing it to burst out after the water level rose.
Uttarakhand, in the western Himalayas, is prone to flash floods and landslides.
Some 6,000 people are believed to have been killed in floods in June 2013 which were triggered by the heaviest monsoon rains in decades.
Sunday’s disaster has prompted calls by environment groups for a review of power projects in the ecologically sensitive mountains.
