How to test water depth/clarity using a Secchi disk
What is it? Water depth is simply the depth of the water at a specific point. In certain areas, water levels have huge effects on ecosystem health. For example, fish spawning.
Why is it important? Water depth naturally fluctuates throughout the season. Tracking depth at times when it is ‘highest’ in the spring and ‘lowest’ in the late summer can give you indications of exceptional drought or flood years.
What does it mean? Every area has different fluctuations and baseline values. Over time, you will begin to understand what is usual and out of the ordinary for your body of water.
How to test
At Water Rangers, we only record water depth when the bottom is visible at a sample location. Please be aware that the location you take depth readings from must be consistent! Use your Secchi disc to record this.
- Lower your Secchi disk until it touches the bottom, ensuring the rope is straight up and down, and there is no slack.
- Pinch the rope, or use a clip to mark where the rope touches the water.
- Record the measurement from your graded reel.
Note: The rope of our Secchi disks measure 20m. Not suitable for deep spots.