Characterization of a Physicochemical Water Quality Reference Status for the Centre-South Forest Region of Cameroon

A study has been carried out on the rivers of the Centre-south forest region of Cameroon in the inter-tropical area of Central Africa. The aim was to determine the variability of the rivers physicochemical state of this area and then to test the aptitude of IPO and SEQ-Eau to rigorously qualify the natural water of this area. Fourteen sampling stations were selected on six streams all located in suburban area less subjected to anthropogenic disturbances. Among these stations, nine were chosen in areas showing the characteristics of reference stations for the study region which are habitat relatively not deteriorated, catchment area uninhabited and sheltered of any urban/industrial activity and absence or scarcity of adjustments of the rivers bed. The reliability of the IPO index is reinforced in its ability to separate distinctly the waters of the upstream area, weakly loaded in organic matters, from those of the middle and downstream areas, moderately loaded. As per its current use, its application on affected mediums in which modified organic matter load is not transported is inaccurate. In addition, the response of reference sites to its application, marked by the low representation of the null organic pollution level class, allows it to be recalibrated for a better match between the response of the index and the observations made on the field. It is apparent from the application of the SEQ-Eau index that no study station belongs to the blue class, indicating acceptable waters requiring only a disinfection treatment before distribution in the drinking water supply network. In their majority, these waters are suitable to all types of rearing, including eggs, fingerlings and adults of sensitive fish species. As with the IPO index, these findings which breach somewhat with the status of reference site of the 9 sampling stations involved, put to test the reliability of the use in the current state of the SEQ-Eau index designed in the temperate region, for the assessment of water quality of the Center southern Forest Region of Cameroon.