Book excerpt: This is the first comprehensive study of an east African lake for thirty years. It represents the culmination of research expeditions which stretch back twenty years and is thus able to pick up long term changes which the individual research activities do not reveal. Lake Naivasha is a tropical lake whose natural fluctuations are now dwarfed by human impacts. Papers show how the irrigation for horticulture and power cooling has reduced the lake depth significantly; exotic arrivals have altered the plant community beyond recognition and its commercial value as a fishery and a tourist feature are reduced by over use. Despite this, the lake has considerable conservation value at present. It provides a different case study in the ever-growing library of the effects of human follies. Lake Naivasha has achieved global importance in the past ten years because its waters are used to sustain the largest horticultural industry in Africa. The book highlights its fragility under such pressure and points out the way towards sustainable use of the water and the ecosystem.