A water quality, biodiversity assessment and community perception analysis of Rungiri reservoir, Kikuyu Kenya.
The occurrence of the Limuru Trachyte in the Kikuyu area of Kiambu District to the north west of Nairobi has led to a lot of rock excavation for building and construction of houses and graveling material for road construction. In the late 1980s, extraction was undertaken in the area during the construction of the Nairobi-Nakuru dual carriage highway, which connects Nairobi with Western Kenya and Uganda. However, due to widespread resource mismanagement associated with the previous regime, a gravel extraction site, known as Rungiri Quarry was excavated beyond the approved contract depth thereby interfering with underground water movement resulting in the development of a water body, the Rungiri Reservoir which is the subject of this research project. The main objective of the environmental study was to assess the quality of water in the reservoir against that of nearby streams and a shallow community well in order to establish the real origin of the reservoir water. The other objective was to assess the current state of aquatic biodiversity in the reservoir in order to gauge the potential for the exploitation and multipurpose development of other natural resources. The final objective was to assess the real life community perception of the reservoir by the Rungiri residents because of their occasional animosity towards the water body due to cases of loss of human life. Data collection involved the use of field measurements for the analysis of water quality and biodiversity and site interviews for the analysis of community perception. The project was primary data oriented and the few secondary data included site maps and rock blasting information. , IV The findings showed that the reservoir and community borehole did not contain good quality water for drinking purposes as provided by World Health Organization (WHO) and the Kenya Bureau of Standards (KEBS) water quality standards. The quality standards for other uses were not considered. The reservoir was found to be eutrophic and in early phase of ecological development thereby making it quite suitable for aquaculture development. It was also found to be home to two water birds namely the Little Grebe and Egyptian Goose. Two types of macrophytes, namely cattails (Typha sp) and the water lily (Nymphae sp) were found to be colonizing the waterbody although the successional progression was found to be rather slow. The residents of Rungiri did not associate the reservoir with any economic advantage. Majority of them perceived it as an environmental obstacle in their midst. However, the analysis of Pearson's Correlation Coefficient ruled out the possibility of the reservoir being a source of disease increases in the area. This is because, even though the regression analysis showed that the relationship between the sources of water and disease outbreaks is positive, the correlation coefficient R square can only relate 0.20% of the diseases to the water sources which is not significant 99.8% being attributed to other factors not covered within the study. Besides, during the study, only four cases of typhoid were reported and no malaria cases reported meaning that the fish in the reservoir could be consuming themosquito lava rendering the reservoir a mosquito free zone. From the findings, it was concluded that the negative community perception towards the water body can be turned around if the community explored ways of exploiting the reservoir as a resource base that would not only be a source of income through aquaculture development but would also boost their protein based nutrition especially at household level. In this regard, it is recommendttd that the local communities be assisted to enable them realize the greater benefits from the reservoir. By so doing, their negative perception will change and will become instrumental in improving the poor state of the environment within and around the reservoir.