Can we save one of the world’s largest freshwater lakes? The Nature of Things reveals how a perfect storm of agriculture, hydro practices, sewage run-off, flooding and marsh destruction has devastated Lake Winnipeg. In a distorted cycle that’s a direct result of human activity, an excess of chemical nutrients in the lake has caused massive algae blooms. The green sludge washing up on the lake's shores threatens not only the lake’s beauty, but also the natural ecosystems underlying it. If humans don’t intervene soon to restore the natural nutrient balance, one of Canada's largest lakes could choke from the bottom up.