Olive mill wastewater causing pollution in the Oum Er Rbia River and potential environmental effects and impact on the Eurasian Otter

The Oued Oum Er Rbia River is one of the major rivers in Morocco. It represents a source of water used for human consumption, culture irrigation, industrial purposes and hydroelectric production in a large part of Morocco. In recent years, the number of incidents of pollution generated by the olive mill wastewater has increased in the Oued Oum Er Rbia River. In this paper, we document the pollution of the Oued Oum Er Rbia by olive mill wastewater in November-December 2020, and we present the potential effects on environment and on the Eurasian otter population. Nine surveys were conducted in November-December 2020 in the Middle Oued Oum Er Rbia. Results of surveys showed that the Oued Oum Er Rbia River was polluted by olive mill wastewater. The disposal of olive mill wastewater into river caused coloration of water and odors. Observations showed that olive mill wastewater affect the wild fauna living in the river. The olive mill wastewater has high organic content and many complex organic materials and has negative environmental effects such as odors, discoloring of natural waters, toxicity, and threat to aquatic life. The pollution of the Oued Oum Er Rbia River by olive mill wastewater may have serious consequences on Lutra lutra and their survival. Several solutions and recommendations were proposed to sustainable management of olive mill wastewater and to conserve the Eurasian otter.