Turbidity

Turbidity is the measure of the clearness of water. The murkier water is, the greater the turbidity. The amount of light that is able to pass through is dependent on the amount of suspended particles that are present. The more suspended solids there are, the less light that is able to pass through to organisms living within the water. Turbidity is important to aquatic life because sunlight is needed for photosynthesis. If turbidity is too great, plants are not able to grow, causing other organisms to die as well.

Testing Turbidity

There are several ways to measure turbidity. The most accurate way is by using an electronic turbidmeter, which measures the amount of light that is able to pass through water. Another way to measure turbidity is by using a secchi disk. The secchi disk is lowered into the water until it can no longer be seen. This depth is then recorded.

Turbidity Levels and What They Mean

Turbidity	Amount of fish per acre	Amount of plankton caught in nets
Less than 25	162	12.8
25-100	94	1.6
Over 100	29	1

Basically, what can be inferred from the table above is that as the turbidity increases, the amount of life decreases. This is due to the amount of light reaching organisms. Without light, plants cannot grow, and therefore not as much fish can survive.

Results

The results of the turbidity levels found in the North Channel of the Chicago River are listed below:

Site	Turbidity
1	44 cm
2	38.5 cm
3	27.5 cm

These results show that the turbidity is fairly good, but can be better. There is a fair amount of sunlight passing through, sustaining a good amount of aquatic life in the water.

Influences

Turbidity can be influenced by soil erosion, waste discharge, urban runoff, channelization, increased flow rate, algae growth, the stir of bottom sediment, and other factors. Several of those factors are influenced by humans as well. Cultural eutrophication significantly decreases the amount of light that is able to pass through because of the algae blooms, which surface the water.
We can decrease the levels of turbidity by reducing the amount of waste we discharge into the water. We can also decrease the amount of fertilizers and other nutrient-high products in order to reduce cultural eutrophication.