Umiam Lake, also known as Bara Pani,[1] is a reservoir in the hills 15 km (9.3 mi) north of Shillong in the state of Meghalaya, India.

When the Assam State Electricity Board conceptualised the hydroelectric project in June 1958, the plan envisioned submerging part of the valley, where Khwan and Umsaw villages were located.

Apart from storing water for electricity generation, the lake also provides numerous ecosystem services at micro, meso and macro levels.

An estimated 40,000 cubic metres (1,400,000 cu ft) of silt enters Umiam Lake every year.

Causes range between upstream encroachments, deforestation, blockage of natural drainage systems, and unscientific mining et al. in the catchment area.