The cleanest part of a watershed is typically the upper reaches, where the water source originates.
This area is often characterized by:
- Minimal human impact: The upper reaches are usually less developed, with fewer roads, farms, and industries.
- Natural filtration: Water flows through undisturbed forests and wetlands, which act as natural filters, removing pollutants and sediments.
- Cold, clear water: The water in the upper reaches is usually colder and clearer due to the lack of pollution and disturbance.
As water flows downstream, it is exposed to more human activities and can become more polluted.
This is why it is important to protect the upper reaches of watersheds to ensure the health and quality of our water resources.
