| Term: | secchi depth |
| Definition: |
The Secchi disk is a device used to measure water transparency in open waters of lakes, bays, and the ocean. A pattern is drawn or painted onto a card or acrylic, mounted on a pole or line, and lowered slowly in the water. The depth at which the pattern on the disk is no longer visible is taken as a measure of the transparency of the water. This measure is known as the Secchi depth and is related to water turbidity. |