Water quality and water-use conflicts in Lake Taabo (Ivory Coast)

Abstract

The Lake Taabo (Ivory Coast, Africa) results of the construction of the Taabo dam on the Bandama River. The changes in the water level of the 69-km2 lake depend on 1) the rainfall linked to alternating dry/wet seasons; 2) the extraction of water for human uses; 3) the discharge of water from the upstream dam and the volumes turbined by the Kossou dam; 4) the various anthropic effects (discharge of untreated waste water from towns and industries, and leaching from agricultural land). The average concentrations of nutrients (NH4-N: 1.1 mg/L, NO3-N: 1.62 mg/L, PO4-P: 10 mg/L, SiO2: 15 mg/L) and chlo- rophyll a (from 4.8 to 16.5 μg/L, average 11.4 μg/L) indicates some degree of eutrophication. The cumulated effects that threaten the ecosystem (degradation of water quality and eutrophication) are such that they are likely to interfere with various water uses. In a context of growing health and environmental concerns in Africa, this study demonstrates conflicts between different uses of this water resource and the urgent need for an appropriate policy including specific monitoring of lake water quality, wastewater control, and a programme to reduce agricultural fertilizers.