Vast blooms of algae are carpeting the River Po, turning sections of the waterway into a thick green mat [1, 2, 3].
The environmental crisis threatens the navigability of Italy's longest river and signals a dangerous intersection of extreme weather and agricultural pollution. As the water becomes choked with organic matter, the ecological balance of the region is put at risk.
The blooms are particularly concentrated in the stretch of the river running through Turin in northwest Italy [2, 4]. Local observers report that the growth has become so dense that it has fundamentally altered the appearance and utility of the water. "It's no longer really a river," a rower on the Po said [2].
Scientists and officials attribute the phenomenon to a combination of factors. July 2026 has seen several weeks of unusually high temperatures [1, 3]. This heat, combined with nutrient runoff from nearby farms, has created ideal conditions for the algae to grow rapidly [1, 3].
The thick layer of algae has made navigation difficult for those using the river for transport or recreation [2, 4]. The presence of farm waste acts as a fertilizer, accelerating the growth of the blooms as the water warms during the summer peak [1, 3].
This event follows a period of intense heat that has strained Italy's water systems. The resulting green carpet prevents sunlight from reaching deeper waters and can deplete oxygen levels, further stressing aquatic life in the Po basin [1, 2].
“"It's no longer really a river."”
The situation on the Po River illustrates the compounding effect of climate change and industrial farming. When extreme heat coincides with high levels of nitrogen and phosphorus from agricultural runoff, it triggers eutrophication. This process can lead to 'dead zones' where oxygen levels are too low to support fish and other aquatic organisms, potentially causing long-term biodiversity loss in one of Europe's most important river systems.
