Water hyacinth threatens Zimbabwe's water supply
The spread of the fast growing water hyacinth weed
in Harare's Lake Chivero is threatening the capital city's main water supply.
The floating weed, one metre tall in places, covers 40 percent of the lake
and is soaking up oxygen and sunlight, killing fish and reducing both the
quality and volume of water in the lake.
Water hyacinth has become a major pest in waterways around the world. Its
rampant growth can destroy native habitats, and high rates of transpiration
through the weed's leaves during summer can cause up to four times the loss of
water from normal water surface evaporation.
Environmentalists in Harare blame the spread of the weed on the discharge of
effluent, particularly raw sewage, into lake Chivero. They have called for an
integrated approach to tackle the problem.
The Environmental Management Act exists to provide strict guidelines on
policy implementation and ensure that stakeholders carry out their mandate with
respect to pollution control and preservation of the environment. Pollution
beyond accepted limits carries a five-year imprisonment penalty.
However, the provisions of the act, passed in March 2003, are still to be
effectively used. As a result, progress on controlling the discharge of effluent
into the lake and efforts to get rid of the hyacinth have so far been
The department of National Parks and Wildlife has been trying to control the
weed by using herbicides and removing it manually and with harvesting machines.
However, these methods require regular follow-up operations to prevent
Progress was hampered because "the effluent has the effect of putting
fertiliser onto something you are trying to get rid of", National Parks
official Edward Mbewe told IRIN.
"The effluent impact is [evident] by the way we are losing fish. There
is now a lack of oxygen for them," he added.
The Zimbabwe National Water Authority (ZINWA), responsible for national water
pollution control, blames the Harare city council and is preparing to force the
council to pay for clean-up efforts.
The water hyacinth is concentrated on the eastern side of the lake, around
the discharge points for the Harare city council's sewage disposal works,
Shamiso Mtisi, a lawyer with the Zimbabwe Environmental Law Association (ZELA)
told IRIN. Mtisi added that ZINWA lacked the resources and manpower to carry out
effective monitoring on the ground.
According to the "polluter pays principle" of the Water Act, ZINWA
can issue permits at a cost to bodies wishing to discharge pollutants into water
sources after industrial use, but the polluted water must be recycled and the
pollutants reduced to harmless levels before the water is released into
ZINWA has stripped the council of its permit, is accusing it of discharging
insufficiently treated effluent into the lake and of doing so without a
A ZINWA official said court action could force the council to release funds
for the upgrading of its sewage works. The Water Act also allows ZINWA to pay
for the clean up of pollution and recoup costs from the offender.
City council spokesman Leslie Gwindi told IRIN the council was carrying out
its mandate with respect to pollution control. He said there had been equipment
failure at two sewage works and the council was "working on them" and
had been "on top of the situation even before ZINWA's involvement".
Gwindi denied that council effluent was chiefly responsible for the growth of
the hyacinth in Lake Chivero. "The weed is feeding on a lot of things. It
is simply difficult to destroy because of the microcosms that exist in the
water," he explained.
Mtisi, the ZELA lawyer, however, said existing waste water treatment
facilities were increasingly overloaded and prone to collapse because of
ever-increasing volumes of waste generated by a growing urban population. The
council, generally lacking in resources, has been struggling to pay for
refurbishments to its water works.
Although litigation induced "a sense of fear in other would-be
polluters", it was costly and time-consuming and it was unclear whether the
penalties were a sufficient deterrent, he added.
Mbewe at the National Parks agency believes litigation to be a waste of
resources that could be better used for pollution control. "While the law
suit against the Harare council is being prepared, the effluent in Lake Chivero
remains. While the court action is happening, there will be more
pollution," he told IRIN.
Barney Mawire of the NGO Environment Africa said a major step in arresting
the pollution in Lake Chivero would be to rehabilitate the swampy wetlands
which, during rainy periods, acted as a sponge and filtered water headed for the
lake. But the increasing use of the wetlands for agriculture was arresting their
ability to clear the water. - IRIN
[This Item may not necessarily reflect the views of the United Nations.
Copyright (©) UN Office for the Coordination of Humanitarian Affairs 2005]
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