The glaciers of Bhutan, which covered about 10 percent of the total surface area in the 1980s, are an important renewable source of water for Bhutan’s rivers. Fed by fresh snow each winter and slow melting in the summer, the glaciers bring millions of litres of fresh water to Bhutan and downriver areas each year. Glacial melt also adds to monsoon-swollen rivers which may be a contributing factor to flooding. Where glacial movement temporary blocks riverflows, downstream areas may be threatened by glacial lake outburst flood (“GLOFs”). Although GLOFs are not a new phenomenon in Bhutan, their frequency has risen in the past three decades. Significant GLOFs occurred in 1957, 1960, 1968 and 1994, devastating lives and property downstream. According to the Bhutan Department of Energy however, the majority of rivers in Bhutan are more susceptible to fluctuation with changing rainfall patterns than to flooding directly attributable to glacier or snow melt.