Bacteriological water assessment of an urban river in Nigeria

The Asa River in Ilorin, Nigeria, which is subject to varied human abuse at its urban fringe areas, was investigated for its pollution status over a period of 2 years. Physical observations including sources of pollution were noted. The degree of faecal pollution was estimated using microbial indicators. Total heterotrophic bacterial counts ranged from 4.5 to 8.5 × 106 ml‐1 with higher counts occurring during rainy seasons. The total and faecal coliforms ranged from 1.6 X 104 to 1.9 × 107MPN index 100 ml‐1 were obtained with higher counts being recovered during dry seasons. Between 62 and 92% of the total coliforms were of faecal origin at various locations. It is concluded that for some kilometres the river, especially during the dry season, is simply an offensive and unhealthy drain. The Asa River and its catchment were therefore identified as a high risk environment for humans.