The Nhieu Loc-Thi Nghe Canal, running nearly nine km through Districts 1, 3, Phu Nhuan, Tan Binh and Binh Thanh before it joins the Saigon River, would have its sludge and garbage removed in three separate time periods, each lasting 75 days, said Pham Ngoc Dung, director of the Management Center of Waterway System under the HCMC Department of Transport.

The removal process would take place in canal sections from Ut Tich Street in Tan Binh District to an intersection of Saigon River in District 1, Dung said.

Around 122,000 m3 of sludge is expected to be removed from the canal and processed at Da Phuoc, the city's largest landfill in Binh Chanh District. The sludge and other waste, flowing from sewers, have accumulated at the bottom of the canal over time and produced a severe stench that negatively affects local residents, said Dung. Machineries used for sludge and waste removal have been placed near Le Van Sy Bridge, it was reported.

"We will not pump the sludge directly onto the banks, but use blends of microorganisms to reduce the stench and prevent it from affecting daily life," said Dung.

The Nhieu Loc-Thi Nghe was a lush river during the 19th century, before it turned into a black canal in the 1960s following the southward migration after the end of the Vietnam War. There had been several cleanup efforts before a grand resurrection project worth more than $200 million with support from the World Bank between 2003 and 2012.

Now regular dumping still threatens the canal.

Over 14 tons of waste, mostly plastic, animal carcasses and plants like water hyacinth, are released into the canal every day. Incidents of mass fish death have been reported every recent year.

Saigon authorities have tried several methods to reduce pollution in the canal, including unblocking water flow, oxygenating water and monitoring water quality.

The southern metropolis has about 170 canals that stretch nearly 700 kilometers. It allocates about VND1.1 trillion ($47.4 million) to maintain its drainage system and VND2.8 trillion (about $120 million) to collect garbage each year, according to the municipal finance department.