222893e

ECONOMIC DEVELOPMENT AND WATERWater cooperation for sustainable utilization:Lake Naivasha, KenyaProfessor David M. Harper, Dr Nic Pacini, Dr Caroline Upton, Dr Ed H. J. Morrison, Mr Richard Fox, and Mr Enock KimintaFresh waters around the world are critical for human welfareyet widely degraded. Lake Naivasha is the world centre forirrigated cut flowers, accounting for over 70 per cent ofKenya’s flower exports (US$400 million) and 3 per cent of its grossdomestic product. Some 5 km 2 of commercial farms are irrigatedfrom lake and groundwater, supplying 40 per cent of the EuropeanUnion market, 25 per cent of which is direct to UK supermarkets.Lake Naivasha and its basinLake Naivasha is the most well-known freshwater resource in Kenyaafter Lake Victoria, because the land around it was subdivided earlyin colonial history and sold to settlers unlike the other freshwaterlake, Baringo, which has remained as government land occupied bythree indigenous communities. Naivasha has long been famous forits aquatic bird diversity, and is popular with residents of Nairobifor weekend escapes and tourists on their way to major destinationssuch as the Maasai Mara National Reserve. Mid-twentieth centurytourist guidebooks describe it as ‘one of the world’s top 10 birdwatchingsites’ and ‘the most beautiful of the Rift Valley lakes’. Suchabbreviated descriptions barely do justice to an ecosystem once asspectacular as this.Anthropogenic changes in the twentieth centuryA commercial fishery was opened in the lake in the secondhalf of the twentieth century after several earlier introductionsof piscivorous American large-mouthed bass andherbivorous East African native Tilapia species. The formeris believed to have exterminated the only native species, asmall endemic tooth-carp, by the 1960s, representing thefirst detectable impact on the lake’s ecology by humans.By the time this endemic fish had disappeared, the firstof several exotic species had arrived by chance. A floatingfern originally from South Africa, named ‘Kariba Weed’because of its dramatic impact on the Kariba reservoir onthe Zambezi, was recorded in the shallow lagoons in the1960s. The exotic with worst impact of all, the LouisianaCrayfish, was deliberately introduced in 1970 by theFisheries Department to diversify the commercial fishery.It ate every native species, plant or animal, beneath thewater surface that could not escape by swimming. Thefishery for it, which exported to Europe, collapsed afterabout six years and has never recovered. The WaterHyacinth, a flowering floating plant also from SouthImage: Nic PaciniWater Ambassadors training on lake ecology at Lake Oloidien, an alkaline lake supporting lesser flamingoes beside Lake Naivasha[ 256 ]