Lake Natron is a salt and soda lake in Arusha Region in northern Tanzania. The lake is close to the Kenyan border and is in the Rift, which is the eastern branch of the East African Rift.This lake is within the Lake Natron Basin.
The lake is fed principally by the Southern Ng’iro River which rises in central Kenya and by mineral-rich hot springs. It is quite shallow and varies in width depending on its water level. The surrounding area receives irregular seasonal rainfall mainly between December and May.The surrounding bedrock is composed of alkaline, sodium-dominated lavas that were laid down during that very period. The lavas have significant amounts of carbonate but very low calcium and magnesium levels. This has allowed the lake to concentrate into alkaline brine.
The color of the lake is characteristic of those where very high evaporation rates occur. As water evaporates during the dry season, salinity levels increase to the point that salt-loving microorganisms begin to thrive. Such organisms include some bacteria that make their own food with photosynthesis as plants do. The red accessory photosynthesizing pigment in the cyanobacteria produces the deep reds of the open water of the lake and the orange colors of the shallow parts of the lake. The alkali salt crust on the surface of the lake is also often colored red or pink by the salt-loving microorganisms that live there.
Most animals find the lake’s high temperatures and its high and variable salt content inhospitable. Nonetheless, Lake Natron is home to some endemic algae, invertebrates, and birds. In the slightly less salty water around its margins, some fish can also survive.
The lake is the only regular breeding area in East Africa for the 2.5 million lesser flamingoes whose status of “near threatened” results from their dependence on this one location.