What management practice is commonly used to maintain water quality in rivers?

Riparian buffer zones are an effective management practice for maintaining water quality in rivers because they consist of vegetated areas along rivers and streams that act as a natural filter. These zones play a crucial role in reducing the amount of pollutants that enter waterways by trapping sediments, absorbing nutrients, and providing a habitat for wildlife that contributes to a balanced ecosystem. The vegetation in riparian zones also helps stabilize riverbanks, reducing erosion and protecting the river's physical structure.

This approach is particularly important for managing non-point source pollution, which is runoff from agricultural fields, urban areas, and other non-specific locations that can carry harmful substances into water bodies. By promoting healthy riparian buffers, water quality is enhanced through natural processes rather than solely relying on engineered solutions.

The other options, while relevant to water management, do not primarily focus on maintaining water quality in rivers in the same way. Dredging is generally used to remove sediment and debris to keep waterways navigable but does not address ongoing pollution sources. Water treatment plants are critical for treating water for human use but do not inherently improve the water quality within rivers themselves. Flood control measures focus on managing excessive water flow and reducing flooding risks, which can sometimes indirectly affect water quality but are not specifically geared toward maintaining