Science - July 1, 2004

Coffee farmers pollute drinking water in Nicaragua

Around the town of Matagalpa in Nicaragua the drinking water is being polluted by coffee farmers and fern growers. Wageningen researchers surveyed the problem and have come up with the recommendation to create marsh areas to clean the water. Irrigation and water management student Joost Jacobi has devoted his MSc thesis to the problem.

The problem occurs in the river basins (cuencas) around the town of Matagalpa in the north of Nicaragua. The water in the rivers is used as drinking water by the townspeople. Upstream lie coffee plantations and fern nurseries, which divert a lot of the river water for use in their production processes. Jacobi did four months of field research for his MSc thesis and discovered a number of issues. β€œThe coffee farmers say that they sometimes divert their waste water to a sedimentation pond, but most of the time they just discharge it back into the river.” The coffee farmers use water to dehusk and wash the coffee beans, and the water ends up with a high concentration of organic material, explains Jacobi. The fern nurseries in the area use pesticides that end up in the river water.

Jacobi conducted interviews among the local population who told him that the drinking water has a bad smell and taste, and many people experience skin irritations after washing with tap water. These problems are worst during the coffee harvest season, so it seems clear that the coffee plantations are the cause of the pollution.

The researchers came up with the advice to create marshes that are capable of cleaning the river in an environment-friendly way. Helophytic filters of reed have been created in various places in the Netherlands to perform a similar function. In Nicaragua the marshes could be placed along riverbanks near the coffee plantations and fern nurseries. The big advantage of marshes is that they require almost no maintenance, an important consideration in Nicaragua, the poorest country in Central America.

The results of the research were presented to the town council of Matagalpa. Jacobi: β€œThe mayor was very enthusiastic, and even asked if we could do something about domestic waste water in the town as well.” The research was recently also presented to Novib (Oxfam Netherlands) and a number of Dutch water boards, who are interested in helping to build up ecological forms of water purification in Nicaragua. |H.B.

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