Sodium Lake is located 8 kilometres east of 70 Mile House.
The lake is a semi-evaporitic playa lake. It is located in the "Green Timber Plateau" area (EMPR Bulletin 4), a semi-arid plateau area averaging 1130 metres elevation which is part of the Cariboo Plateau and host to several playa lakes. The area is underlain by alkaline plateau basalt flows of the Miocene to Pleistocene Chilcotin Group, mantled by a thin cover of glacial till and glaciofluvial sediments. Annual precipitation averages between 300 and 400 millimetres (EMPR Paper 1991-1).
Soda Lake (Hutchison Lake in EMPR Bulletin 4, page 22) contains sodium carbonate-rich brine and the muddy shoreline is heavily encrusted with natron. Brine covered an area of approxiamtely 6 hectares to a maximum depth of 3 metres in October of 1937. The specific gravity of the brine was 1.0685 and it contained 7 per cent solids conposed of 96.3 per cent sodium carbonate, 3.3 per cent sodium chloride and 0.1 per cent sodium sulphate (EMPR Bulletin 4, page 23).