The lake is part of the East African Rift system. The Tugen Hills, an uplifted fault block of volcanic and metamorphic rocks, lies west of the lake. The Laikipia Escarpment lies to the east.
Water flows into the lake from the Mau Hills and Tugen Hills. It is a critical habitat and refuge for more than 500 species of birds and fauna, some of the migratory waterbird species being significant regionally and globally. The lake also provides an invaluable habitat for seven fresh water fish species. One,Oreochromis niloticus baringoensis (Nile Tilapia), is endemic to the lake. Lake fishing is important to local social and economic development. Additionally the area is a habitat for many species of animals including the hippopotamus (Hippopotamus amphibius), crocodile (Crocodylus niloticus) and many other mammals, amphibians, reptiles and the invertebrate communities.
While stocks of Nile Tilapia in the lake are now low, the decline of this species has been mirrored by the success of another, the African Lungfish which was introduced to the lake in 1974 and which now provides the majority of fish output from the lake. Water levels have been reduced by droughts and over-irrigation. The lake is commonly turbid with sediment, partly due to intense soil erosion in the catchment, especially on the Loboi Plain south of the lake.
The lake has several small islands, the largest being Ol Kokwe Island. Ol Kokwe, an extinct volcanic centre related to Korosi volcano north of the lake, has several hot springs and fumaroles, some of which have precipitated sulphur deposits. A group of hot springs discharge along the shoreline at Soro near the northeastern corner of the island.
Several important archaeological and palaeonto logical sites, some of which have yielded fossil hominoids and hominins, are present in the Miocene to Pleistocene sedimentary sequences of the Tugen Hills.
The main town near the lake is Marigat, while smaller
