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Pollution, siltation choke Lake Mutirikwi

13 Jul, 2020 - 00:07 0 Views
Pollution, siltation choke Lake Mutirikwi

The Herald

George Maponga Masvingo Bureau
A strong stench wafts into the thin air, forcing passers-by to scramble for small pieces of cloth to cover their faces.

The hyacinth that continues to spread its tentacles like an octopus threatening to overrun the whole Mucheke River — which bisects the ancient city of Masvingo — tells a story of something terribly wrong with the water.

Crossing Chimusana Bridge, along Mucheke River, is now a complete nightmare for scores of the pedestrians who daily cross it to and from work in the city.

The river has lost its lustre and struggling to recover its soul following relentless attacks on its life by firms in the industrial area that continue to deposit effluent in one of Lake Mutirikwi’s biggest tributaries.

A few kilometres from Mucheke to the east, trouble is also brewing as the once mighty Pokoteke River is also now a shadow of its former self.

The braided river snakes timidly on its natural sojourn into Lake Mutirikwi, but its evidently clear that something is also haunting its soul.

Heavily silted, the once magnificent, effervescent and mystical perennial pools that used to decorate its course are no longer there.

Pokoteke’s journey into Lake Mutirikwi, today is now mostly to vomit loads of silt and limited amounts of water, a situation that has brought Zimbabwe’s second largest inland dam close to its knees.

The twin evils of pollution and siltation are clearly and gradually snuffing life out of this once mighty dam which at the peak of its powers used to be the most eminent hinge upon which irrigation in the Lowveld was held.

Close to six decades after its commissioning, Lake Mutirikwi is battling to breath, with its lungs of life restricted by rampant siltation and pollution.

Besides casting a dark shadow over irrigation in the Lowveld and areas adjacent it, siltation means availability of portable water for the fast-growing Masvingo City is no longer guaranteed in the event of successive droughts that spawn poor inflows into the water body.

Pollution has also decimated aquatic life, principally fish, which continues to fall prey to poisonous effluent.

Fish populations have shrinked massively owing to curtailed breeding which resulted from depletion of food sources owing to effluent being dumped into the lake and its tributaries.

Provincial manager for the Environmental Management Agency (EMA) Mr Milton Muusha contends that environmental degradation in Lake Mutirikwi’s catchment is an albatross around the future survival of the water body.

The dam’s catchment comprised 26 wards scattered across parts of Gutu and Masvingo districts.

EMA was worried about the appalling situation at the dam which is of immense economic and ecosystemal value.

“The agency together with all other relevant departments have done a thorough assessment of the area that makes up Mutirikwi Dam catchment,” said Mr Muusha.

“The assessment revealed that land degradation is rife and this is threatening the well-being of this fragile, but very important natural resource and ecosystem.”

Illegal settlements that have spawned land degradation in the dam’s catchmentarea  have been blamed on unscrupulous village heads in the business of selling land.

Mr Muusha noted the scourge of land degradation was at the core of the lake’s problems.

“Land degradation in the catchment area manifests in the form of stream bank cultivation and siltation of the rivers and streams that feed into Lake Mutirikwi,” he said.

“Erosion through gullying, sheet erosion, as well as lack of soil and water conservation works on cultivated land, deforestation, wetland degradation and water pollution, are also some of the biggest challenges affecting the dam.”

Assessments done two years ago by EMA and other stakeholders showed that streambank cultivation was rampant along streams and rivers feeding into the country’s second largest inland water body.

“The assessment, done in 2018, revealed that then, a huge stretch of rivers and streams in the catchment were affected by streambank cultivation,” Mr Muusha said.

“This is mainly in form of gardens and other cultivation activities along the main rivers and streams that feed into the dam. This malpractice is found on rivers and streams such as Mutirikwi, Shagashe, Munyambe, Pokoteke, Nyamaungwe, Mazare, Shakashe, Nyamukono and Mucheke, among others.”

Poor soil conservation was also a serious setback in the catchment area.

This promoted large-scale siltation in the lake, thereby threatening its survival.

“A total of 23 gullies were identified, covering a total area of 3 598 hectares in the dam’s catchment,” said Mr Muusha.

“More than 90 percent of land under cultivation has no form of soil and water conservation measures, which promotes high levels of erosion on such arables.”

“In terms of river siltation, the most affected river is Munyambe in Hwede village in Zimuto which has a total stretch of 20km that is severely silted with silt coming from upstream.

“The other affected rivers are Makurumidze, Mutirikwi in wards 8 and 32 of Masvingo district. In Gutu, Shakashe River is the most silted, especially in Southdale village, in ward 32.”

EMA was also concerned about the fast depletion of wetlands on the lake’s catchment.

Farming contributed the biggest threat to their survival.

Mr Muusha bemoaned deforestation in the Mutirikwi catchment area, which was also slowly causing the lake’s death.

“The total area covered by wetlands in Mutirikwi River catchment is 47ha, with 49 wetlands,” he said. “Of these, 31 are moderately degraded, while 15 are severely degraded. One remains stable with only two wetlands undisturbed. Most of these wetlands are found in communal areas and because of their location, their threat comes from agricultural activities.

“The cumulative total area affected by deforestation in the catchment area in 2018 was 110.4 hectares. Most of the deforestation is taking place in Summerton villages 1 and 2, ward 6 and at Clunny Farm in Zimuto communal lands.

“These three areas had a total of 94,5ha affected by deforestation. The major driver of deforestation here is firewood demand in Masvingo City.”

EMA also monitored pollution levels in all of Lake Mutirikwi’s tributaries.

While the situation was still fine in some of the streams, those that pass near Masvingo City were in a bad state as recurrent power outages sometimes lead to the discharge of raw sewage into the streams.

“The agency (EMA) also monitors pollution levels on all the feeder rivers and streams that drain into Lake Mutirikwi and water samples are collected every month from these feeders,” said Mr Muusha.

“Along Mazare, Mutirikwi and Pokoteke, the sampling results are always in blue, meaning the water is environmentally safe from pollution.

“However, we sometimes get green (low hazard) and yellow (medium hazard) sample results for Shagashe and Mucheke rivers, especially when there are breakdowns in the sewer pumping system, or power outages. Samples collected from the dam are always blue (safe from pollution).”

To combat the scourge, EMA has since teamed up with other stakeholders, including communities within the catchment area, and came up with a Local Environmental Action Plan (LEAP) for the entire catchment.

“The LEAP contains a package of action plans to be undertaken by the locals, the local authorities and Government, including all development partners to address identified problems,” said Mr Muusha.

Among the measures is pegging and enforcement of conservation works in the entire catchment area together with demarcation of gardens and cultivation away from stream banks.

Wetland rehabilitation programmes and law enforcement to curb malpractices like deforestation, streambank and wetland cultivation and water pollution were also being implemented.

According to LEAP, Government departments and community leaders should be at the forefront of these programmes which among other things push for alternative energy sources to curb deforestation in the catchment.

There was also need to prosecute village heads who illegally parcel out land because rising population pressure in the catchment continued to sound a death knell for Zimbabwe’s second largest inland water body.

Dwindling fish stocks in the lake coupled with a very limited increase in the water levels over the past five years have been described as ominous signs of the lurking danger on the future survival of Lake Mutirikwi.

With a lake area straddling about 90 square kilometres, Lake Mutirikwi was built between 1958 and 1960 principally to irrigate cane fields in the Lowveld and supply Masvingo City with water.

Its catchment area covers about 3 900 square kilometres and this giant colossus supports agriculture, tourism, recreation and fisheries in the Lowveld.

If no action is taken to curb unsustainable environmental practices, Lake Mutirikwi will be choked to death under the weight of twin evils – pollution and siltation.

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