To the unsuspecting eye Mukuvisi River is just an ordinary watercourse, snaking through Harare’s eastern suburbs. It is by turns narrow, sluggish, foul smelling, shallow and deep. In some places it vanishes altogether, disappearing into reedy swamps, then re-emerging further downstream.
From its source in the Cleveland wetlands, the Mukuvisi is the longest river flowing throughout the year, uniting eight tributaries which trickle into it along its way south. As it meanders from the Cleveland Dam area through Msasa and the Mukuvisi Woodlands, it changes shapes and sizes. In places its banks are home to illicit breweries and sex havens, in others it is a hangout for drifters. Worse still, in other areas it opens to industrial depositions, silt from dumpsites and spillage of millions of cubic metres of raw sewage.
Professor Christopher Magadza of the University of Zimbabwe (UZ) knows the river well. “Since the 70s, when I started teaching Applied Hydrobiology at the UZ, the Mukuvisi River has been a faithful teaching aid on pollution. I have always been able to guarantee a convincing demonstration of pollution on this river, in spite of at least two Water Acts, and other statutory instruments, concerning water pollution control.
Professor Magadza mourns the destruction of the ecology of this beautiful river through human activities. He says the chief pollutants of the river have been industries that have been dumping their toxic waste for a long time.
“It is a known fact that there are factories dumping their waste into the river over the years,” says Prof Magadza, who is also a member of the Lake Environmental Committee.
According to Environment Africa (EA), the loss of open spaces adjacent to the river due to unplanned developments and illegal dumping of rubbish that occurs along the riverbank, has posed many challenges to the river’s ecology.
The organisation notes that Mukuvisi’s natural system has been negatively modified and the river’s capacity to purify itself naturally has been seriously compromised. Excessive resource use has led to the establishment of alien plant species with a corresponding decrease in biodiversity.
It says that the public has strong negative perceptions of the river and thus it has little recreational use.
Engineer Theodore Nherera of the Zimbabwe National Water Authority (ZINWA), says the river is usually the recipient of industrial pollution because disposal of wastes into it is cheap and convenient.
The main sources of pollution range from pulp and paper mills to fertilizer factories and granulation plants, abattoirs, textile, steel and clothes manufacturers. These industrial processes produce large quantities of different kinds of pollutants.
“The underlying problem is the lack of strong industrial environmental management ethics and poor waste water treatments by companies along the river,” says Nherera.
“To reverse these negative trends much depends on the implementation and monitoring of environment laws that safeguard the river passages,” he adds.
A City of Harare engineer, Phillip Pfukwa, says pollution is varied along the river, and its danger depends upon the types and amounts of waste that reach the aquatic environment.
Rivers are integral to the land they flow through. In many cases, they help to eliminate the waste products of terrestrial ecosystems. However, this natural process is often disturbed by the introduction of excessive amounts of waste matter, especially when a river system crosses a heavily industrialized or populated zone.
The perilous state of the river mirrors the health barometer of the residents of Harare.
Lake Chivero, one of the dams supplied by Mukuvisi River, has been shown in recent studies to have levels of microcystin ranging between 19µg per litre to 23µg per litre. This is an average of 20µg per litre more than the World Health Organisation recommended limit of 0.01µg per litre in drinking water.
Microcystin is water-soluble and is normally not removed by standard water treatment procedures.
“Microcystins cause cancers, intestinal disorders and damage human male testicular chromosomes. Offspring sired by males with such microcystin-related disorders are liable to be genetically abnormal,” enlightens Prof Magadza.
Until the river is allowed to breathe again, its inhabitants and those who rely on it will live in danger.
Do you know the rivers that run by you?
We’ll be highlighting different rivers that flow through Harare over the coming months. Tell us about yours.