 With the retreat of glaciers in the Himalayas , a number of glacial lakes have been created . A growing concern is the potential for GLOFs researchers estimate 21 glacial lakes in Nepal and 24 in Bhutan pose hazards to human populations should their terminal moraines fail . One glacial lake identified as potentially hazardous is Bhutan 's Raphstreng Tsho , which measured 1 @.@ 6 km ( 0 @.@ 99 mi ) long , 0 @.@ 96 km ( 0 @.@ 60 mi ) wide and 80 m ( 260 ft ) deep in 1986 . By 1995 the lake had swollen to a length of 1 @.@ 94 km ( 1 @.@ 21 mi ) , 1 @.@ 13 km ( 0 @.@ 70 mi ) in width and a depth of 107 m ( 351 ft ) . In 1994 a GLOF from Luggye Tsho , a glacial lake adjacent to Raphstreng Tsho , killed 23 people downstream . 
