Secchi Discs

Secchi Discs are designed for the measurement of the relative turbidity and clarity of water body. This disc is constructed of powder coated steel, and is finished in alternating black and white quadrants of acrylic paint. The disc operates as such: the disc is lowered into the water on a graduated line. The depth at which the disc is no longer visible is reorded. The disc is then raised, and recording of the depth at which the disc reappears should be made. The mean of these two recordings is considered to be the limit of visibility. Although the disc is unable to provide an actual measure of light penetration, it is useful in providing a rough index of visibility for comparative purposes.