ウィニペグ湖
Lake Winnipeg ranks as the 11th largest lake by surface area; excluding the Caspian Sea, Lake Winnipeg would be the 10th largest freshwater lake in the world. The lake consists of three well-defined regions, the larger North Basin, the smaller South Basin, and the connecting body of water defined as the "Narrows", all of which are greatly affected by algae blooms. The surrounding watershed drainage basin is roughly forty times larger than the lake’s surface area, this ratio is higher than any other major lake in the world; this makes Lake Winnipeg susceptible to excessive nutrient levels. Because Lake Winnipeg holds a considerable small volume of water, the water quality is determined by manmade structures and high nutrient loading.