Did you know that the easiest, most inexpensive way to monitor water quality in a lake is with a simple white disk? This measurement tool is called a Secchi disk. It is a metal disk, 8 inches in diameter that has a cord attached to the middle. This cord has 6 inch increments marked on it. Each foot is marked in black, while each half foot is marked in red. The way to take a Secchi disk reading is to lower the disk on the cord into the water until you can’t see it anymore. Then, you slowly pull it back up until you see it again. You average these two depths from the surface of the water to the disk and that is called the Secchi depth. [Read more…]