Secchi Readings

Volunteers collect water transparency data using an 8-inch, circular, all-white metal plate attached to a calibrated rope. This tool is called a Secchi disk. About once a week during the summer, volunteers boat to a designated spot on their lakes to collect transparency readings. The volunteer lowers the disk into the water until it is no longer visible and notes that depth from the markings on the rope. The disk is then lowered a little further and then raised back up until it is just visible. This second depth reading is averaged with the first, and the final number is recorded.