Community-based water quality monitoring in Zimbabwe

Deka River is a main river in Hwange District in Western Zimbabwe and is a life vein for community members from the villages close to Deka, where they feed their livestock, use the reeds for breeding baskets and catch fish which are their main source of protein. Due to a lack of functioning drinking water boreholes, community members also consume Deka River water.

In and around the town of Hwange in Western Zimbabwe, bituminous coal has been mined and processed since colonial times. Effluents from the industrial activities are channeled into Deka River. In recent years, the water quality of Deka has allegedly deteriorated and numerous fish kills afflict the river each year. Villagers also reported livestock dying after herding around Deka River and complained about stomach aches and other symptoms after consuming the river water. In 2017, community members and local civil society initiated a multi-stakeholder mediation process in Hwange involving government and the industry. Even though the Deka River pollution is broadly acknowledged by the industrial stakeholders, their individual contribution to the overall pollution remained unclear and highly debated.

To address the missing link between cause and effect, community members and scientists in Hwange district formed a citizen science team. In collaboration with the University of Zimbabwe, scientists from ETH Zurich trained 13 community members in Hwange District to take water samples and measure water quality parameters. In a joint effort over 1.5 years, community monitors and scientists took close to 800 water samples in Deka River, main effluent tributaries and at point sources of the pollution. Additionally, the team installed automated water quality measurement devices in Deka River and in the main effluent channel leading out of Hwange. Community monitors also took fish samples to assess the food they are consuming. All samples were analyzed in laboratories in Switzerland.

The extensive dataset collected by community monitors and scientists allowed us to show the main sources of the pollution and attribute responsibilities to industrial players. The primary source of pollution is acidic metal-rich groundwater from abandoned underground mine reaching the surface. Illegal mine water dumping from active mine sites accentuates the problem and results in fish kills. National guideline values of fresh water quality are consistently violated, by up to a factor of 70, leading to a public health risk when consuming Deka River water and fish.