The specific colour of a freshwater course depends on factors like geology, vegetation, human activity, and weather conditions.
- Clear (blue): Pure or clean water with little sediment or algae appears clear or takes on a blue hue, especially in deeper areas, due to the way light scatters and reflects.
- Green: Algae or phytoplankton growth, common in nutrient-rich waters.
- Brown/Tan: Suspended sediments (like clay or silt) from erosion or runoff, particularly after rain.
- Teal/Turquoise: Freshwater bodies fed by glacial melt can appear turquoise due to fine rock flour.
- Black/Dark Brown: Tannins from decaying organic matter (common in swampy or forested areas.
- Gray or Murky White: Could result from clay or industrial discharge.`