Due to a rapid increase in Zanzibar’s in population, as well as a lack of proper sewage treatment, water quality and eutrophication have become serious issues on Unguja. These issues not only threaten public health, but also threaten the health of nearby coral reefs. This study aimed to quantify the presence of fecal indicator bacteria (enterococci) and the levels of eutrophication in the surface waters of Stone Town and its vicinal reefs, while also placing results in a larger context with respect to seasonal monsoonal variations. Meetings were held with members of the Zanzibar Municipal Council, and a survey of both tourists and Zanzibaris was conducted in order to understand the public’s level of awareness regarding sewage treatment and water quality. When data from bacterial enumeration was compared with recommended levels of enterococci for safe recreational waters, values revealed that Stone Town’s water is unsafe for public swimming. Moreover, measured concentrations of ammonium from Chapwani Island exceeded those tolerable by healthy coral ecosystems. These results indicate that sewage pollution is causing, and will continue to cause damage to Stone Town’s waters unless a new method of sewage treatment is created.
Environmental Health and Protection
Moynihan, Molly, "Water Quality and Eutrophication: The Effects of Sewage Outfalls on Waters and Reefs Surrounding Stone Town, Zanzibar" (2010). Independent Study Project (ISP) Collection. 827.