Put on the rubber hip boots, pick up the bottle and wade as close to mid-stream as possible.
Face upstream and take the cap off the bottle. Dip the bottle into the stream. The bottle should be as close as possible to the middle of the stream depth.
Fill the bottle with water. Put the cap back on the bottle and wade carefully back to shore.
Place the white plastic square on the ground in the shade.
Place the Secchi tube on the white square.
Swirl the water sample in the bottle slowly for three seconds. Remove the cap and pour the water into the tube until it is at the top of the ruler on the outside of the tube.
Close one eye and look straight down into the Secchi tube with the other. If the symbol at the bottom is visible, record the height of the water in the tube according to the ruler on the outside of the tube. If the hourglass symbol is not visible, slowly pour out a tiny amount of water from the tube and again look into the tube to see if the symbol is visible. Repeat pouring water from the tube until you can just see the symbol.
Record the measurement on the Secchi tube's ruler in the notebook.