The lake is located at 0°42' - 0°50'S /36°16' - 36°26 'E and has an area of 15,600ha (including islands), at an altitude of 1884m asl. It is believed that some 6000-13,000 years ago, Lake Naivasha was part of a much larger lake that encompassed the present lakes Elementaita and Nakuru, and discarded down the Rift Valley southwards. The lake is a fresh water lake with a catchment of 2,378 km2. Other temporally watercourses descent from the forested slopes of Oldoinyo opuru ridge, and extends eastward from Mau escarpment, across the valley north of the lake. The principle water supply to the lake is from Aberdare Mountains. Two rivers drain these areas and enter the lake. The Malewa river has a catchment of 1,730km2 and provides 90% of the inflow. Ground water seepage, particularly along the north and northeast shores is reputedly responsible for up to 16% of the total influx. There is probably a sub-terranean drainage system, but this has yet to be verified.
Lake Naivasha was designated as a RAMSAR site in 1995 and is managed by the local property owners under the Lake Naivasha Riparian Association formed in 1934. The lake provides diverse habitats for a variety of mammals, birds and fish (tilapia, black bass, and cray fish).Fishery is conducted for both domestic and commercial purposes. Commercial fishery makes an annual production of 75 tonnes valued at Kshs 2.5 million.
The lake provides approximately 50xlO.6m3 of water for irrigation which supports one of the most expansive horticultural industry in this part of the world and which employs more than 250.000 people. The horticulture exports are the second largest foreign exchange earner for the country after tourism. Tourism is also a major sector in the lake and its catchment basin.
The lake environment is fragile but dynamic and supports tourism and geothermal power generation from deep-rooted stream jets among other economic activities. Lake Naivasha's biodiversity is critically threatened by human induced factors, including: habitat destruction, pollution (from pesticides, herbicides and fertilisers), sewage effluent, livestock feeding lots, acaricide, and water abstraction. A population of over 250,000 people lives around the lake. This high population has encroached wetlands and converted them into agricultural lands, residential areas, and tourist hotels. The continued harvesting of papyrus along edges has in particular destroyed the natural state of the lake. Current research findings show that the lake cannot sustain further development activities on the scale seen over the last fifteen years.