Lake Natron lies to the north on the border between Kenya and Tanzania. Manyara is also shallow, with a maximum depth of 3.7 m (Hughes & Hughes 1992). To the east of Lake Eyasi lies Lake Manyara. Even though permanent springs lie along the lakeshores, their waters evaporate quickly.
The Sibiti River occasionally flows into the lake but its waters usually evaporate before reaching the dry lakebed. The lakebed of Lake Eyasi is usually dry, but may occasionally flood up to a depth of 1 m (Hughes & Hughes 1992). In the Tanzanian rift valley, the largest saline and soda lakes are Lakes Eyasi, Manyara, and Natron. These soda lakes vary in shape from broad, shallow pans to narrow, deep depressions (Livingstone & Melack 1984). Many of the soda lakes fluctuate in size and change in water salinity with dry and wet periods. Whereas the pH of freshwater lakes ranges from 6 to 8, that of the soda lakes ranges from 9 to 12. Many of these lakes are endorheic, and high ambient temperature in the rift valley increases the rate of evaporation, thereby enhancing the water’s alkalinity by raising the concentrations of Na, HCO 3 -, and CO 3 2. Streams that feed the lakes flow over highly alkaline volcanic rocks, bringing natron (a naturally occurring salt consisting of sodium carbonate and sodium bicarbonate) into the lakes’ waters (Cole 1994). Saline and soda lakes are more abundant in the Eastern Rift than in any other African ecoregion. The lakes lie in the primarily evergreen bushland portion of the Eastern Rift Valley. These lakes are salty and some of them have high concentrations of fluoride and sodium carbonate salts. There are also other small lakes (< 20 km 2) on the valley floor, including Lakes Solai, Kabongo, Kwenia, Sonachi, Oloidien and Ol’bolossat in Kenya and Bdrangida, Lelu, and Momera in Tanzania. The main saline or alkaline lakes are Bogoria (42 km 2), Nakuru (49 km 2), Elementaita (19 km 2), and Magadi (105 km 2) in Kenya, and Natron (900 km 2), Manyara (470 km 2), Eyasi (1050 km 2), Barangida and Singidani in Tanzania. The major freshwater lakes from north to south are Baringo (130 km 2) and Naivasha (156 km 2) in Kenya, and Babati, Burungi and Kitangiri in northern Tanzania. There are also several artificial wetlands, such as dams, fish ponds, sewage lagoons and irrigated fields.
Shallow lakes, rivers and streams, hot and cold water springs, marshes, swamps, and salt pans occur within the ecoregion. Xeric freshwaters and endorheic (closed) basins