Reducing Risks of Contamination Breaching the Drinking Water System through Catchment Sensitive Farming in Eastern Nigeria

Otammiri River is the primary raw water source for the Imo State Water Corporation (ISWC), a public water supply agency. The Corporation supplies drinking water to the residents of Owerri, the capital city of the State. The Otammiri River is one of the many rivers in the larger Anambra-Imo River basin. However, upstream agriculture and deforestation activities have continued to diminish the ability of the river to continue to play this role in the future. The combination of intensive agriculture and deforestation, in addition to sand mining and residential activities continued to pose enormous threat to the over 2 million Owerri residents who depend on ISWC for their long term water needs.Agriculture poses the greatest threat based on the enormous amount of fertilizer (organic and inorganic) used on commercial and private farms. The result is widespread Nitrates, a by-product of nitrogen-based farm fertilizer, animal manure, wastewater and leaky septic tanks. On top of these are wasteful and inefficient agricultural practices, including very low knowledge of fertilization application. For example, it was observed that many vegetable farmers can apply as much fertilizer as they want, within feet of the river.

Further observations and surveys in the course of this study showed that the leading source of nitrate pollution in many parts of the larger Anambra-Imo River basin-nitrogen fertilizer - is not regulated. For example, agriculture nitrate and phosphate has in combination to the region’s high intensity sunshine and warmth, triggered blue-green algae bloom in the utility’s reservoir. The result has been incidents of toxic compounds released by the algae such as cyanotoxins gradually inundating the city’s water-treatment plants. Already taste and smell has been reported by consumers. Such toxins especially Microcystins and nodularins are feared and can be dangerous for humans and animals. As at the time of the pilot, it was already posing technical challenge for ISWC managers, for example, many purification methods used by the ISWC was incapable of removing the nitrate contaminants from the water. The result is that the quality of water supplied by ISWC became a public health challenge. An incident of poorly managed catchment has also been reported by and the resultant expensive cost of water treatment which it posed. Read more...............