Environmental and socio-economic impacts of pollution by Eichhornia crassipes (Mart.) Solms in the waters of Dams No. 2 and No. 3 in the city of Ouagadougou, Burkina Faso

Wetlands, essential habitats for biodiversity, provide important resources and environmental services and play a role in combating climate change. However, in Burkina Faso, dams No. 2 and 3 in Ouagadougou, in the central region, Kadiogo province, are experiencing degradation due to the invasive presence of Eichhornia crassipes. To assess the environmental, social, and economic impacts of the invasion of Eichhornia crassipes on the local populations around dams No. 2 and 3 and on their activities, a methodology was set up. This methodological approach was based on a mixed-methods strategy, including, on one hand, semi-structured interviews with local residents and institutional officials, and on the other hand, a water sampling campaign. The study results revealed that these dams were being filled in by an invasion of Eichhornia crassipes, leading to decreased fish yields, the emergence of waterborne diseases, disruptions in boating activities, congestion of irrigation infrastructure, reduced navigable areas, and the appearance of diseases in livestock. The most concerning pollution parameters are suspended solids (14.8 mg/l to 22.2 mg/l), nitrites (0.166 mg/l to 0.233 mg/l), Chemical Oxygen Demand (128.4 mg/l to 59.4 mg/l), 5-day Biological Oxygen Demand (40.2 mg/l to 20.4 mg/l), fecal streptococci (16,760 CFU/100 ml to 13,000 CFU/100 ml), fecal coliforms (28,053.8 CFU/100 ml to 23,226.4 CFU/100 ml), and Escherichia coli (860 CFU/100 ml to 720 CFU/100 ml). The analysis results did not reveal any significant difference between the different sampling points for all parameters, except for pH and TSS. These results are important for the preservation of these wetlands and the implementation of an ecological management strategy aimed at restoring these environments.