Elmenteita is a shallow alkaline lake (1,800 ha; maximum depth 1.9 m) lying on the Rift Valley floor some 20km south-east of Nakuru town. It is fed by the Kekopey hot springs at its southern end, and two small streams, the Meroronyi and Kariandusi, flowing from the eastern plateau. The surrounding landscape is characterized by dramatic rocky faults, volcanic outcrops and cones. Rainfall is erratic and averages less than 600 mm/year. To the east, the lake is flanked by small-scale agriculture, while several large ranches surround the remainder. The northern and south-eastern lakeshores are open and flat, a spectacular cliff rises to the north-east, and the western shores are broken and rocky. The natural vegetation is mainly Acacia and Tarconanthus camphoratus bushland interspersed with Themeda triandra grassland. Patches of Acacia xanthophloea woodland occur near the shore, and formerly covered a large area south of the lake. The IBA consists of the lake and its surrounding shoreline, including the hot springs and the cliffs, and the Soysambu Wildlife Sanctuary (5,400 ha), part of the Delamere Estate, that abuts the lake to the north and west.
See Box and Table 2 for key species. The threatened, restricted-range Prionops poliolophus occurs in the surrounding woodland (where it may be resident), and Euplectes jacksoni is a seasonal visitor nesting in the tall grassland. The lake consistently holds internationally important populations of Phoenicopterus ruber (1991–2001 January mean: 5,600) and P. minor (1991–2001 January mean: 140,300) and Recurvirostra avosetta (1991–2001 January mean: 1,440). At least 69 waterbird species are recorded, including 29 Palearctic migrants. Fish have recently spread from the peripheral hot springs to the main lake, but even before this Elmenteita often hosted large numbers of Pelecanus onocrotalus. Up to 8,000 pairs have bred there when water levels are high and rocky outcrops in the eastern sector are flooded to form islets, on which the birds can safely nest. The pelicans move daily to Lake Nakuru (IBA KE049) to feed. Phoenicopterus ruber have also bred at Elmenteita in the past, but have been displaced by pelicans in recent years. There have been occasional, but unsuccessful, breeding attempts by Phoenicopterus minor. The woodland and bushland are rich in birdlife (over 400 species have been recorded), particularly raptors. Globally threatened species additional to those shown in the Box are Falco naumanni, which occurs on passage, and vagrant Aquila clanga and Parus fringillinus. Regionally threatened species include Podiceps cristatus (which has nested here recently), Casmerodius albus (an important non-breeding site, with regularly more than 50 and as many as 156 counted in January 1994); Trigonoceps occipitalis; Hieraaetus ayresii; Stephanoaetus coronatus; Polemaetus bellicosus; Buphagus africanus; and Euplectes progne.
Non-bird biodiversity: Soysambu holds good populations of large mammals, including an introduced population of Giraffa camelopardalis rothschildi. The snake Bitis worthingtonii, endemic to the central Rift Valley above 1,500 m, is known from here. The cichlid fish Oreochromis alcalicus grahami, endemic to alkaline lakes in this part of the Rift Valley,occurs in the hot springs and has recently spread to the main lake.
Pressure/threats to key biodiversity
Private ranches, including the Soysambu Wildlife Sanctuary, cover c.75% of the shoreline, and this portion is generally well protected. Subsistence farming on the eastern side is leading to increased siltation of the lake from soil erosion, while increased offtake from the Meroronyi stream and destruction of vegetation in the catchment are reducing water inflows. There has been substantial destruction of the Acacia xanthophloea woodland on the south-eastern shores. Overgrazing on the ranchland during periods of drought, particularly in the south-eastern sector, accelerates erosion after heavy rain. Soda extraction and sand mining on the eastern shores are limited in scale at present but may be a serious problem in future. Tourism at Elmenteita is increasing, the main attractions being the scenery, birdwatching and the chance to see unusual animals by night (night driving is not permitted in National Parks). There is a tourist lodge (Lake Elmenteita Lodge) on the escarpment above the lake and a tented camp (Delamere’s Camp) in the Soysambu Wildlife Sanctuary. At the moment tourism exerts little pressure on the lake, and is a force for its conservation.