Illegal alluvial gold mining and environmental degradation in steep slopes and on river banks in the East Usambara Mountains, are destroying water sources for over 300 000 Tanga city residents.

The Tanga Urban Water Supply and Sanitation Authority (Tanga Uwasa) says it loses a total of Sh15.2 million (US$ 6 800) every day in revenue collection and increased costs of water treatment as a result of a serious increase in turbidity in the Mabayani Dam, the major source of water that feeds Tanga City.

The Tanga Uwasa Managing Director, Joshua Mgeyekwa said here that mud flowing from Muzi River which feeds into Zigi River that, in turn, flows into Mabayani Dam has increased turbidity of the water from the normal 100 NTU (mud level units) to 600 NTU.

“We have been forced to cut water production because the kind of chemicals we use for treatment of water cannot clean a large amount of water at one time,” Mgeyekwa said.

Reduced water supply

The normal daily water supply from the Mabayani Dam and Mowe Water treatment plant has been cut from between 29 000 and 30 000 cubic meters of water per day to between 20 000 cubic meters and 21 000 cubic meters per day resulting in water rationing, a phenomenon Tanga residents have not been used to.

He said that the authority is losing Sh13 million (US$ 5 800) per day in revenue collection, while costs of water treatment chemicals has trebled from Sh670  000 (US$ 3 00) per day to Sh2.2 million (US$(9 80).

Mr Mgeyekwa said that Tanga residents are being forced to drink water whose colour is not clear and sometimes muddy.

He said that it was difficult to measure the right dose of treatment chemicals because turbidity was not stable changing frequently thus affecting the quality of water.

The cut in the supply has also caused the coastal city, which has enjoyed a stead water supply of 24 hours, to experience water rationing.

“The problem has not only caused financial loss, less water supply and increase in the cost of treating water, but it has tainted our record as one of the best water utilities in Africa,” said Mgeyekwa, whose utility is a holder of an ISO certification.

Those who visited the Mabayani Dam at Pande, the main water source for Tanga City residents saw the dam, whose water has turned red due to increased load of mud from Zigi River.

The capacity of the dam has been reduced in 39 years by 7% from its original capacity of 7.3 million cubic meters due to siltation caused by destructive environmental tendencies.

To deal with the problem of increased mud Uwasa has decided to clean the Dam, but this could take two weeks.

“We have been forced to open the washout valve of the Dam to reduce mud which settled in,” said Mr Mgeyekwa, adding that it takes about two weeks to clean.

It would also take one month for the water pipes supplying water to customers which have been filled with mud to return to their normal state. But the situation is beginning to stabilize.

Uwasa has established a special desk to enable customers report problematic areas and get help flushing water pipes. The major problem, according to observations made by a team of Tanga Uwasa officials, is caused by Muzi River that flows into Zigi River at Kwatango.

Cooperating with locals is key

Environmental destruction in the river is in the form of illegal mining activities being conducted along the banks of the river. Mgeyekwa said that an Uwasa team is working day and night to make sure Tanga water customers get clean water.

“Our efforts would now be directed to Muzi and Semdoe Rivers as we did in Amani where we found fatalities due to illegal activities,” he said.

He said the clean water flowing from Amani shows that Uwasa has succeeded in educating people living in river source areas on the importance of conserving and protecting the environment including the rivers for their own benefits.

They will also make trials of another type of water treatment chemicals that can clean a larger volume of water at one time. Installation of the pump that would pump the chemicals is on-going and next the trial would begin soon.

Alternatives to East Usambara water sources

Uwasa has started to draw water from boreholes to bridge the gap in supply. The Authority has also a long term project to draw water from River Pangani that would also benefit Korogwe, Muheza and Pangani Districts.

On the problem of farming along river banks, Mgeyekwa said he is engaging the Pangani River Basin Water Organisation (PBWO) on the need to enforce laws and regulations.

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