Environmental factors controlling contamination of alternative water supply points in the Lefock semi-urban watershed, Cameroon Western Highlands

Due to the poorly managed water network of the Dschang municipality (West Cameroon), the peri-urban population of the Lefock watershed, frequently, consumes doubtful quality water from alternative supply points (WASPs) such as springs, wells, boreholes, and river waters. In this context, this study aimed to explore the influence of neighboring environmental conditions on the contamination of these resources. Thus, 22 WASPs and their immediate perimeter were characterized (within a 10 m radius), both from physiographic (nature of bedrock, type of WASPs, soil type, land use) and anthropogenic (presence of pit latrines, domestic wastewater, domestic breeding, agricultural activities, wild garbage dump, washing clothes on-site) points of view. In parallel, chemical (NO 3 − , NH 4 + , PO 4 3− ) and bacteriological (faecal coliforms, faecal streptococci, total coliforms, and E. coli ) contamination parameters were analyzed and compared with the World Health Organization (WHO) standards. Multiple Factor Analysis (MFA) was performed, using water quality variables as input combined with environmental data as supplementary data. This approach first revealed that waters from WASPs were generally of very poor bacterial quality due to proximity to pit latrines, domestic wastewaters, and/or agricultural surfaces. Second, chemical contamination was greater where WASPs were neighboring to agricultural plots and/or domestic wastewaters. The MFA showed that the chemical degradation of WASPs mostly occurs at the watershed scale rather than very local scale, and was representative of diffuse and likely long-term pressures over the resource. In contrast, bacteriological contaminations were better governed by immediate contexts and appeared to result from the combination of anthropogenic and physiographic constraints. Regarding the influence of physiographic characteristics, the type of soil and the nature of the WASPs are the main influencing factors. The hydromorphic context accentuates the general vulnerability, while an increasing vulnerability related to the type of WASPs was observed: spring < well and borehole < river. These results indicate that structural poor water management, combined with a limited consideration of local environmental specificities threaten sustainability of this resource in semi-urbanized zones over heterogeneous aquifers and the water security of its population. This argues for a strong twofold education effort for managers and end-users of the resource.