The Imja Glacial Lake is the second largest glacial lake in Nepal Himalayas after Tsho Rolpa and is listed high among potentially dangerous glacial lakes. It lies at an altitude of 5000 metres above sea level and is fed by the debris-covered glaciers of Imja, Lhotse Shar and Amphu Lapcha. This lake is the headwater of the Imja River.

The Imja lake is a relatively new lake which was formed in the 1950s. Scientific data has revealed an alarming growth in the size of the lake in the last decade. A few small ponds started forming as shown in a 1955-63 Schnider map. According to data from a survey in 1992, the length and width of the lake was 1.3km and 0.5km respectively. The average depth was 47 m and the maximum was 99m. The lake occupied an area of 0.60 square km. The accumulation of water was estimated at about 28 million cubic m. The next survey of Imja in 2002 showed that the lake had expanded to an area of 0.86 square km, 28 per cent larger than the last survey.

The sharp increase in the size of the lake attracts attention to the risk it causes from glacial lake outburst flood (GLOF). GLOF occurs when the natural moraine walls along the glacial lake cannot withstand the water pressure caused by the water accumulated in the glacial lake causing the moraine walls to break and a huge volume of water and debris to flow down with a like a flood causing massive loss downstream.