Effects of untreated sewage on marine environment-A case study of Karachi

The objective of the paper was to identify the impact of untreated municipal sewage on the marine environment along the coast of Karachi. Karachi, the financial capital of Pakistan, is facing a serious sanitation and sewage crisis. About 471 million gallon per day (MGD) of municipal wastewater is discharged into the sea without treatment. It produces over 12,000 tons of solid waste every day and about sixty percent of solid waste is dumped in designated landfills and remaining solid waste remains in the streets and roads. Results concluded that heavy discharge of untreated municipal wastewater into Arabian Sea; deteriorate the coastal areas of Karachi, production of marine fisheries become sluggish, high risk to human health and extinction of four types of mangrove forests. It was observed that the average annual growth rate of marine fish catch remained 0.68 percent during 2000-19 which is a very a nominal growth rate. Whereas, the average annual growth rate of inland fish catch remained 3.55 percent during the same period. The habitat on the Gizri stream, Manora Island, Clifton and Sea view beaches have been deteriorated and most of the territories of these reservoirs are deprived of a congenial environment. Marine life is contaminated with lead and consumption of seafood by people can cause a health hazard for the residents of the city. In order to solve the biggest sewage problem in Karachi, it is recommended that the projects initiated under the Greater Karachi Sewerage Plan be implemented as a priority, and efforts should be made to functionalize all treatment plants at earliest. It is necessary to create an independent high-power committee to monitor the future wastewater flow into the Arabian Sea and hold them responsible for not fulfilling their statutory role in managing the sewage system for the collection, pumping, treatment and disposal of domestic and industrial waste.