Turbidity is a measure of the degree to which light is scattered by suspended particulate material. In other words, it refers to how clear the water is. It provides an estimate of the the muddiness or cloudiness of the water due to organic and inorganic matter, microscopic organisms, pesticides, cadmium, mercury, or lead found in the water. The greater the amount of total suspended solids in the water, the murkier it appears and the higher the measured turbidity.

    Turbidity cannot be determined as good or bad, many animals live well in highly turbid water. Some animals live well only in water with low turbidity. There is no measurement on how high or low the turbidity should be,but very high levels of turbidity for a short period of time are less dangerous then lower levels of turbidity for a long period of time.

Procedures:

1. Obtain a secchi disk and mark every centimeter with a permanent black marker, up to about 50 centimeters.

2. Go out into water around knee height.

3. Slowly lower the secchi disk into the water until it disappears and no part of it can be seen.

4. Record the depth of when it disappears.

5. Without moving the disk, slowly raise it up until it can be seen again, or until it reappears.

6. Record the depth at which it reappears.

7. Repeats steps 3 - 6 two more times for a total of three trials.

Alternate procedure

1. Using a turbidity meter and an Explorer, calibrate the probe with distilled water first by inserting the cuvette into the probe and pressing the green button on the probe. The light will blink, then place the standard 100NTU into the probe and press the button again.

2. The probe should read 100 NTU on the Explorer display module

3. Obtain a sample of water in the cuvette and place in the probe. Read the NTU and record.

4. Press the play button on the Explorer to store the data