THE on-going uncontrolled urban agriculture in Harare seriously threatens the water sources and the quality of the city's drinking water, environmentalists have warned.
The warning comes at a time when the Harare City Council is struggling to provide clean water to residents due to the shortage of foreign currency to buy chemicals for water purification.
Water sources that are under threat from urban agriculture include Manyame River, Hunyani River and Lake Chivero, water bodies that provide Harare's drinking water.
Once the rivers and streams silt up, the environmentalists said, "there would be a shortage of water forever".
A lecturer in the department of social science and agricultural engineering at the University of Zimbabwe confirmed that Harare's water sources were under threat from uncontrolled urban cultivation.
He stressed however, that raw sewage disposal into water sources by the city council was the main cause of pollution. It is estimated that about 70 percent of the raw sewage finds its way into Lake Chivero.
"Though the discharge of raw sewage by the City Council is the major reason, the effects of urban farming, carried without due regard to conservation measures and council by-laws, also contributes significantly to water pollution," said the lecturer.
Takawira Mubvami, a scientific programme co-ordinator with Municipal Development Programme (MDP) said water pollution is worsened by the fact that Harare "sits on its own watershed," resulting in all waste flowing into its water sources.
He said urban agriculture was being practised "willy-nilly" causing in environmental degradation and pollution.
"It is difficult to stop because of urban poverty but as an organisation we are advocating for sustainable urban agriculture policies," said Mubvami.
A study by the Environmental and Development Studies (ENDA-Zimbabwe) three years ago also noted that urban agriculture posed a serious threat to the urban environment.
"All sites (visited areas) had unacceptable levels of erosion. In addition, almost 90 percent of Harare's farmers use chemical fertilisers and nearly a third of 'off-plot' cultivation takes place near streams, swamps - leading to water pollution through runoff and leaching," said the study.
The UZ lecturer said the use of chemicals also resulted in high nitrogen content in the soil and would promote vegetative growth in the water. In the case of Harare, this has led to the growth of the notorious hyacinth weed, which is threatening Lake Chivero.
Mubvami urged farmers to stop using synthetic fertilisers and use organic fertilisers such as manure, which do not pollute water sources.
The problem of pollution is exacerbated by the fact that the council is the major culprit. Ignatious Chombo, the Minister of Local Government, Public Works and National Housing, has openly castigated the Harare City Council for being the major polluter through discharging raw sewage into its water sources.
Apart from being the major polluter of water sources, the council is also accused of not enforcing its bylaws, particularly those relating to urban farming and pollution.
As a result, there has been a phenomenal growth of urban agriculture. The local authority relaxed by-laws governing urban agriculture in 1993, in a bid to alleviate poverty linked to the Atructural Adjustment Programme without due regard to environmental consequences.
Spokesperson for Harare City Council, Cuthbert Rwazemba, could not be reached for a comment, as his mobile phone went unanswered.
But Mubvami said urban agriculture is now recognised as long as the farmers abide by the council bylaws.
From 1990 to 1994, the amount of land under cultivation in Harare nearly doubled - to about 16 percent of the city's area - and has been rising rapidly ever since.
In its latest report the Famine Early Warning Unit (FEWN) noted that Harare was clearly experiencing high rates of urban growth leading to problems of unemployment, poverty and homelessness.
And as a result of the economic problems, said the report, urban agriculture has become an alternative source of food and income for urban poor. The urban low-income households, affected the most by the current economic crisis in the country, have sought to supplement their family incomes and improve their family nutrition through urban agriculture.
However, experts say this pollution of water sources by urban farmers, City Council and industrial bodies, has increased the cost of water purification and treatment for the city.
In its bid to provide clean water, the city is presently using at least seven chemicals to purify the water. In the 2004 budget, at least $815 billion has been earmarked for the purchase of the chemicals.
Unfortunately, the experts noted, the financial burden would be passed on to the ratepayers, who will have to fork out more for what are clearly the council's misdeeds.
Several environmental studies have recommended that urban planners develop policies that enhance sustainable city agricultural development, rather than seek ways to eradicate the practise.
They also advocate for the provision of agricultural extension services, particularly to the most disadvantaged sectors of the urban population as well as imposing stiffer penalties for stream bank cultivation.