Answer :
Final answer:
The smelly pollutant primarily polluting Lake Washington was untreated sewage in the mid-1900s due to factors like eutrophication from fertilizers. The Clean Water Act of 1972 helped improve water quality. Pollution from various sources continues to impact water globally.
Explanation:
Untreated sewage was the smelly pollutant primarily polluting Lake Washington near Seattle, Washington in the mid-1900s. Sewage, leaking sewers, lawn fertilizers, pesticides, and herbicides contributed to the pollution of water bodies.
Eutrophication caused by excessive nutrients from sources like fertilizers led to algal blooms that depleted oxygen in water bodies, resulting in fish kills and dead zones. The Clean Water Act of 1972 mandated wastewater treatment and pollution control, improving water quality in the U.S.
Pollution from industrial, municipal, and agricultural sources, including animal feedlots, crop fertilizers, and chemicals, continues to impact water quality globally, affecting aquatic ecosystems and human health.
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