Agricultural pollution is not the only source of water contamination. Sewage, industrial pollution, and residues from automobile exhaust all are swept downstream into rivers and ultimately the ocean.
Video Summary: Modern society has interfered with the natural water cycle for centuries. Pollution from agricultural, residential, and industrial sources has contaminated rivers and oceans, and problems with water management have caused aquifers and reservoirs to become depleted. This video proposes potential solutions to improve handling of water in the future.