This article examines the water quality of the Odra River near Szczecin before, during, and after the 2024 flood wave caused by the Boris low-pressure system. Data from the Chief Inspectorate for Environmental Protection (CIEP) and independent measurements taken during the flood were compared. Before the flood, the river faced significant ecological challenges, including the presence of "golden algae" (Prymnesium parvum) and hypoxia. In several monitoring stations, approximately 40% of dissolved oxygen (DO) measurements were below 3 mg/l, a critical level for fish survival. The overall water status was classified as "below good" (within the meaning of Polish regulations) mostly due to high salinity. The passage of the flood wave reached its qualitative peak on October 1, showing a sharp increase in turbidity, total suspended solids (TSS), and dissolved organic carbon (DOC). Simultaneously, the immense volume of water caused a dilution effect, leading to a temporary drop in conductivity and chloride concentrations to levels significantly lower than annual averages. The study emphasizes that while southern reservoirs and German polders prevented major flooding in the lower Odra, the ecosystem remains vulnerable. The Międzyodrze wetlands seems essential natural filters and polders that are crucial for future flood management and water quality improvement.