Which practice is identified as the best way to prevent eutrophication?

• A. Increase fertilizer use.
• B. Build dams.
• C. Buffer zone.
• D. Dredge sediments.

Answer: (C)

Preventing eutrophication hinges on controlling nutrient inputs, especially nitrogen and phosphorus, before they reach water bodies. Eutrophication happens when excess nutrients fuel algal blooms, which block sunlight and, when they decompose, deplete oxygen and harm aquatic life.

A buffer zone, or vegetated buffer along a stream or river, is the most effective way here. The plants and soil in this strip act as a natural filter: they take up nutrients for growth, microbial processes immobilize nutrients in the soil, and the dense vegetation slows runoff. The result is less fertilizer and soil that would otherwise wash into the water, fewer sediments carrying nutrients, and more opportunity for water to infiltrate rather than runoff quickly into streams. This directly reduces the nutrient load entering the water and helps prevent algal blooms.

Other options don’t address the source or can even worsen the problem: increasing fertilizer use adds more nutrients; building dams changes water flow but doesn’t remove nutrients and can create other issues downstream; dredging sediments can release stored nutrients back into the water and disturb habitats.