Wetlands are crucial for biodiversity and are highly productive ecosystems, as they involve a variety of biological and non-biological factors in their functioning. Understanding these systems requires, in addition to other characteristics, a physical and chemical description of their waters, as well as an analysis of the specific structure of the species inhabiting these environments. This study focused on describing the marshy waters of Merja of Fouarat, which is registered under the Ramsar Convention. The lake consists of three parts, each varying in size and flood duration. The results revealed that the organic pollution index for this environment is very high. Based on these findings, the researchers recommended the preservation of the area due to its significant ecological and environmental importance.