secchi disc definition

A Secchi disk is a black and white colored disk used to determine water clarity. The disk is lowered into the water. The point, at which you can no longer distinguish the black and white, is called the Secchi depth.

Secchi Reading and Lake Nutrient Status:

  • Over 5 metres Oligotrophic – unenriched, few nutrients - clear water
  • 3.0 to 4.9 metres Mesotrophic – moderately enriched, some nutrients - water less transparent, lacking clarity
  • Less than 2.9 metres Eutrophic – enriched, higher levels of nutrients - cloudy, murky water,