A salt lake, or saline lake, is a lake with a lot of sodium chloride and other dissolved minerals in the water. It is often defined as three grams or more of salt per litre. In some cases, salt lakes have more salt than sea water: they are called hypersaline lakes. An alkaline salt lake with a high content of carbonate is called a soda lake.
- subsaline 0.5–3 ‰ (parts per thousand)
- hyposaline 3–20 ‰
- mesosaline 20–50 ‰
- hypersaline greater than 50 ‰
Salt lakes form when the water flowing into the lake, containing salt or minerals, cannot leave. This is because the lake is endorheic (a dead end). The water then evaporates, leaving behind any dissolved salts. This increases its salinity. Salt lakes are an excellent place for salt production. High salinity will also lead to a unique flora and fauna in the lake. Sometimes the large amount of salt means there is little life in or near the lake.
If the amount of water flowing into a lake is less than the amount evaporated, the lake will eventually disappear and leave a dry lake: a 'playa', salt flat or salt pan.