Lake Nakuru-Kenya: A review of Environmental Impacts of Landuse Changes

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1 Sengupta, M. and Dalwani, R. (Editors) Proceedings of Taal 2007: The 12th World Conference: Nakuru-Kenya: A review of Environmental Impacts of Landuse Changes Raini A. Jackson* 1 and Andrew Kulecho 2 1 Programme Director, FlamingoNet, P.O. Box 13493, Nakuru , Rift Valley-Kenya. 2 Chief Laboratory Technologist, Nakuru Water Quality Testing Laboratory, Akuru, Kenya *Corresponding author jraini2002@yahoo.com. ABSTRACT Nakuru is one of a chain of endorheic, hypereutrophic, alkaline-saline lakes in the eastern arm of the Rift Valley in Kenya. It is a shallow lake and an extreme ecosystem in which intervals of complete dryness alternate with periods of flooding and high water. The lake is a centrepiece of one of the main National Parks of Kenya and famous world wide for its spectacular bird life. Over 450 species of birds, as well as 70 species of mammals have been recorded. There are 178 registered industries in Nakuru, generally small- to medium-scale enterprises, manufacturing and processing a variety of products, such as batteries, textiles, tanned leather, paints, detergents, animal and human foodstuffs, and agro-chemicals. Like most cities, Nakuru is a huge consumer of resources, and a prodigious producer of waste. The Park falls within category 1 of the African Development Bank EIA guidelines and IUCN category II. Results from an Environmental Assessment Programme initiated in 1993 reveal that the concentrations of pollutants could have a significant impact on the ecology of Nakuru. In some cases (e.g. Pb, Cu, gamma BHC, dieldrin, paraquat) the concentrations are already sufficiently great to cause concern. This paper results from a literature survey, desk study and laboratory studies carried out to identify environmental and other parameters important for the continued maintenance and management of Nakuru ecosystem. INTRODUCTION Nakuru catchment basin is a closed drainage system of 1800 km 2 located on latitude S longitude E. It s bounded by Menengai Crater ( m a.s.l) to the North, Bahati Highlands to the Northeast, Mau Escarpment to the West, Eburru crater to the South and gentle grasslands between Nakuru and Elementeita basins lie to the East. At the sump of this catchment basin is the solar powered and insulated Nakuru National Park (LNNP), the buffer zone between human activities and the lake. The Nakuru catchment is a unique ecosystem containing a variety of habitats that include an alkaline lake which is a home to millions of flamingos often referred to as the greatest ornithological spectacle on earth, the largest Euphorbia forest stand in East Africa, a wildlife rich savannah and highland moist forests. The nature, geology, climate, soils and ecology all interact to make this a vulnerable and fragile ecosystem. The area is a rich agricultural region with a diversity of agricultural activities. Nakuru town is the fourth largest and one of the fastest growing metropolitan in Kenya. The catchment area covering 1,800km² has a variety of land use systems that include urban and industrial centres, small and large-scale intensive agriculture, and ranching, forestry and wildlife conservation. Agriculture industry, mining, transport and urban development are the foremost sources of environmental contaminants in Nakuru. The economy of the Nakuru catchment basin is heavily dependent on agriculture. In Kenya, agricultural sector accounts for 28.7% of the country s Gross Domestic Product and provides 50 to 60% of export earnings. Agro-chemical use is a well established facet of agricultural production; and the volumes of agrochemicals used each year are increasing. Kenya alone imports over 7000 metric tons of pesticides annually. This figure excludes pesticides provided under the tutelage of aid schemes and means of illicit trade. In addition to pesticide formulations registered with the Pest Control Products Board (PCPB) of Kenya, a copious number of pesticide formulations are sold in the country without having undergone any screening at government research stations. Some of these products reportedly contain severely restricted or banned organochlorines such as DDT, aldrin, dieldrin, lindane, and pentachlorophenol. In addition, the approved use of internationally banned chemicals includes applications on large cash crop plantations. The environment will be exposed to even greater burdens of nutrients and other contaminants. The government is striving to industrialize the region in line with the Vision Industrialization is occurring in an environment of foreign and local investment. Although confronting difficulties the industrial sector is growing slowly and has gone beyond the pursuit of simple substitution. Industry in Nakuru now covers an array of enterprises including mining, plastics processing,

2 vehicle assembly, rubber and leather processing, textile and battery manufacture, food processing and oil recycling. The last three decades also have witnessed the proliferation of small scale artisan business collectively refereed to as the Jua Kali sector as well as small manufacturing concerns engaged in carpentry, vehicle repair, metal work and textiles. At both ends of the scale, developments in the industrial sector have contributed to better quality life, but they have also increased the risk of exposure to hazardous chemicals and industrial waste products. Increasing concentrations of substances originating from industrial sources have been detected in air, water, and soil throughout the Nakuru catchment basin and pollution incidents arising from accidents and indiscriminate disposal of wastes have been reported in nearly every industrial center. Government initiatives to control and regulate the trade in industrial chemicals and waste disposal are constrained by lack of human and financial resources. Environmental impact assessments (IEAs) for new development projects are now mandatory in Kenya. However, even as this legislation is now in place, glaring deficiencies exist in our capacity to carry out objective and accurate EIAs and audits, or to enforce existing legislation. In these circumstances, the threat of environmental damage from industrial pollution looms large. The proliferation and burgeoning of urban centres throughout the basin presents its own set of environmental problems and dilemmas. Urban areas are prodigious producers of waste, and since most industrial zones are also located close to (and often spawn) urban developments, municipal authorities have the responsibility for disposing of both domestic and commercial/industrial waste. In recent years, it has become evident that the growth in waste generation has out-stripped the capacity of local authorities to remove and safely dispose of urban waste. The situation pre-disposes urban, peri-urban and even more distant environments to adverse effects in water, soil and air. The problem of environmental pollution has not been adequately addressed in Nakuru town. Progress has been restricted in the realm of legislation. Little priority has been given to pollution controls and contaminant monitoring, and almost no opportunities exist for developing capacity in these areas. Ecosystem health and sustainable development are inextricably linked. A holistic approach to the maintenance of ecosystem health must include monitoring and mitigating the impacts of the myriad of environmental contaminants. Scope of the Study This paper results from literature survey and an ecological assessment of the Nakuru basin carried out under SAPS II in order to characterize the environmental conditions of the basin and to identify major pollution sources. The EIA surveys included the collection and analysis of water, sediment and soil samples from Nakuru and other soda lakes in the Rift Valley ( Bogoria, Elementeita and Sonachi), tributaries of Nakuru, former and existing dumping sites in Nakuru, effluent and industrial solid wastes from: major industries, the water supply system, the sewage treatment works, and background soils in the area. The total numbers of samples amounted to 96 water samples and 47 sediment and soil samples. In addition, interview surveys of 106 households and 20 factories were carried out to identify sanitary problems, levels of environmental education and awareness, and pollution control measures by industries. The existence of serious pollution sources in Nakuru poses significant environmental risks to the people and ecosystem in the Nakuru basin. The EIA was thus designed to achieve the following objectives: To investigate the pollution levels of Nakuru and its basin jointly with local environmental researchers, to obtain reliable, common reference environmental data, To carry out a model environmental survey to become the basis for future monitoring activities, and to obtain the information required to design a long-term environmental monitoring system. METHODOLOGY Sampling In total, 51 water samples and 18 sediment/soil samples were collected and analysed. The sampling activities were carried out during the period of April 19 to June 26, 2002, this time; the survey was designed to investigate the environmental conditions both before and after a large rain event. water samples were collected from two layers: a surface layer (0-30 cm) and bottom layer (within 30 cm of the lake bottom). The lake sediment samples were collected from the surface of the lake bed. Rivers in the area are shallow and there was no need to take stratified samples. Therefore, one water sample was collected in each location. All water samples were collected both before and after rainfall. Sediment samples and soil samples were collected once from surface layers (depth 0-30cm) before rain had occurred. RESULTS Table 1. shows a comparison with previously reported data of heavy metals in the Nakuru water. The results of studies in 1995 and 1999/2000 are two to three orders of magnitude higher than the results of this study and that of the water quality standards. The reasons for the differences in the results between this Study and the data previously 2242

3 reported are difficult to identify due to the nonavailability of detailed background data. Pesticides None of the lake water samples showed any detectable concentration of pesticides and other organochlorine chemicals tested for at this time, namely PCB compounds, DDT, DDD, DDE, gamma-bhc, aldrin, dieldrin, heptachlor, toxafene, fenitrothion, parathion, malathion and paraquat. The result differs from that of WWF in 1999/2000 in which DDT, DDD, DDE, gamma-bhc, aldrin and heptachlor were detected. Sediment Quality to the results, Nakuru sediment contained higher median concentrations of Cd, Pb and Zn than the other lakes. The results are well correlated with the results of the water analysis, where the levels of Cd, Pb and Zn were rather high in Nakuru. The concentrations of other heavy metals were not particularly high in Nakuru compared with the other lakes. SUMMARY OF RISK FACTORS The following factors have been identified as presenting risk of serious perturbation to the ecology of Nakuru, and hence it s national and international status as a National Park and as a Ramsar site. (1) Heavy Metals Table 2. shows the summary of heavy metal content in all lake sediments. According Table 1. Comparison with previously reported data of heavy metals - Nakuru water Parameter Nakuru n=16 n=6 Bogoria Elementeita n4 n=2 Sonachi Cadmium (Cd) 2.4 ( ) 1.5 ( ) 1.0 ( ) <0.4 <4 Lead (Pb) (2-5) Zinc (Zn) 76.5 (8-126) 21.5 (12-33) 43.0 (28-77) 77 (39-115) Total Chromium (T- Cr) 18.5 (7-556) (36-1,290) 4.5 (4- - 6) 12 Arsenic (As) 35.7 ( ) 90.6 ( ) 160 ( ) 31.8 ( ) Copper(Cu) 38 (6-59) 40 (29-84) 51 (5-51) 20.5 (15-26) Manganese (Mn) 90.5 (5-552) (77-215) (86-206) 30.7 ( ) Nickel (Ni) 4.5 (2-16) 6.5 (5-8) 5.2 ( ) 2.85 Table 2: Summary of heavy metal content in all lake sediments Parameter / Quality Standards WWF EIA SAPS II SAPS I Dutch** ER-M** 2001 Study NOAA ppm mg/l mg/kg mg/kg mg/kg mg/kg Cadmium(Cd) Lead (Pb) Zinc (Zn) T.Chromium (T-Cr) H. Chromium (Cr) nd nd nd nd nd nd Arsenic (As) Selenium (Se) Mercury (Hg) Copper (Cu) Nickel (Ni) Note)* Dutch intervention value for soil remediation estimated based on average clay and organic carbon contents of 36% and 3.5%. ** Adverse biological effect level of marine sediment; National Oceanic and Atmospheric Administration (NOAA), ER-M: Effects range-median (se DOE, 1997). 2243

4 POLLUTANTS Heavy metals ELEMENT KNOWN 1MPACTS DANGER LEVELS COMMENTS Lead (Pb) Negative to eukaryotic algae, fish Flamingos and other birds Manganese (Mn) Iron (Fe), Selenium, (Se),Titanium (Ti), Nickel (Ni), Chromium (Cr) Potentially toxic at greater than trace levels Se, Fe, Ni and Mn are essential micronutrients, with positive effects at trace levels. All these are potentially toxic at greater than trace levels Positive effects at trace levels Levels in feathers of birds exceeding 5000 ppb cause sub-lethal effects. Levels exceeding 12 ppm in Flamingo liver associated with mortality. - - Levels of Se in water >80 µg/1 toxic to algae and >200 µg/1 toxic to rotifers and fish Further work is required in order to determine specific levels of toxicity and maximum safe levels for the management of Nakuru Arsenic (As) Positive at trace levels.. Mercury (Hg) Negative to birds Levels should not exceed 0.1 ppb in water or 1.5 ppm in sediments. Levels should not exceed 0.3 ppm in fish Copper (Cu) Negative at higher levels to Spirulina, other Cyanobacteria, bacteria, diatoms and fish Cadmium (Cd) High levels negative to Cyanobacteria, rotifers fish and birds. Bioaccumulate in invertebrates Zinc (Zn) - Positive at trace levels. High levels negative to algae, diatoms crustacea and fish Pesticides (insecticides, herbicides) Levels should not exceed 0.05 ppm in water or 10 ppm in sediments Concentrations >0.05 ppm in water and >50 ppm in sediments potentially toxic to algae ppm in water cause adverse effects on Cyanobacteria and aquatic invertebrates. Levels in kidney of birds of 200 ppm is associated with mortality 1.5 ppm toxic to Anacystis nidulans LD50 for minnow 500 µg/l (at ph 8-8.5) Present levels already represent a threat to algal populations, to fish and to birds, including flamingos Further work is required in order to determine specific levels of toxicity and maximum safe levels for the management of Nakuru Present levels already exceed those toxic to algae and fish Present levels in water already exceed those toxic to certain Cyanobacteria zooplankton and fish Present levels in water potentially lethal to fish ELEMENT KNOWN 1MPACTS DANGER LEVELS SOURCES Organophosphates negative to cyanobacteria, fish and birds Copper-containing fungicides negative to algae Herbicides: negative to algae Levels in water Paraquat negative to fish should not exceed 0.5 ppm. Present levels are cause for concern Other pollutants Eutrophication; slight Detergents positive or negative impact on algae from this source town effluent Miscellaneous organic Direct toxicity to all Oil, spillages, etc. (from 2244

5 compounds organisms; negative to aquatic organisms Turbidity is potentially negative to algal Sediments, productivity. Pollutant suspended matter content negative to aquatic organisms. Eutrophication potentially Inorganic nutrients negative to algae due to (nitrogen and phosphorus) change in species composition. urban runoff) From surrounding hills during rain periods) From fertilizer, runoff etc. and town effluent) PHYSICO-CHEMICAL CHANGES (ENVIRONMENTAL) 1. Water level: negative to flamingos if above 4.2 m or below 2.0 m (due to changes in area of water and of salinity affecting growth of algae) and to rhino if flooding excessive of if previously unflooded areas become submerged. 2. Area of lake and of shallow water (< 0.5 m deep): negative to rhino and other wildlife if area of lake exceeds current maximum. 3. Salinity and alkalinity: negative to Spirulina if below 10 ms; optimum range 15-30mS/cm. 4. Nutrient status and dynamics: potentially negative if balance (of phosphorus and nitrogen) favours other algae, which then replace Spirulina. Effect compounded if salinity also changes. This needs more research at L. Nakuru. 5. Organic matter: dissolved, particulate: similar impacts to that of nutrients. Little is known, especially role of the bacteria, so further research necessary. CHANGES TO BIOTA REFERENCES Chapman, D. (editor) Water Quality Assessment. A guide to the use of biota, sediments and water in environmental monitoring. Chapman & hall, London. Domsch, K..H Effects of pesticides and heavy metals on biological processes in soil. Plant and soil 76: Greichus, Y.A., Greichus A., Ammann, B.D. and Hopcraft, J Insecticides, Polychlorinated Biphenyls and metals in African lake ecosystems. III. Nakuru, Kenya. Bulletin of Environmental Contamination and Toxicology 19: Kairu, J.K Pesticide residues in birds at Nakuru, Kenya. International Journal of Salt Research, 3: K allqvist, T. and Meadows, B.S Toxic effect of Copper on algae and rotifers from a soda lake ( Nakuru, East Africa). Water Research 12: Vareschi, E. and Vareschi A, Ecology of Nakuru (Kenya). V. Production and consumption of consumer organisms. Oecologia (Berlin, 61: Mangat Patel and Partners, 1996, Nakuru Environmental Impact Assessment. Natural resources Institute, Chatham Maritime, Kent. SAPS Team for JBIC, Final Report for Special Assistance for Project Sustainability II (SAPS II) for Greater Nakuru Water Supply Project in the Republic of Kenya. 1. Algae, bacteria, meso- and macro-fauna: nothing known of the role of bacteria in the lake ecosystem, especially nutrient cycling, mineralization, transport from sediments to water, etc. Further research in this subject is required before impacts can be assessed. 2. Algal and bacterial toxins: negative to aquatic organisms and any wildlife in contact with the water or sediments. ENVIRONMENTAL CHANGES Other habitats, breeding or feeding grounds, etc. Development and changes in areas outside the National Park will have negative effects on most migratory birds, especially the flamingos, if other feeding and breeding areas are disturbed. 2245