Turbidity

Background Information

Turbidity refers to how clear or how cloudy the water is. The lower the turbidity, the clearer the water. Turbidity can be a result of suspended solids such as clay, silt, plankton, industrial wastes, or sewage in the water. High turbidity may be caused by soil erosion, waste discharge, urban runoff, flooding, dredging operations, channelization, increased flow rates, algae growth, or even too many bottom-feeding fish (such as carp) that stir up bottom sediments. If water becomes too turbid, it loses the ability to support a wide variety of plants and other aquatic organisms.

Suspended solids reduce the amount of light that can pass through the water. As less light penetrates the water, photosynthesis slows releasing less oxygen into the water. If light is blocked to bottom dwelling plants, they will cease to produce oxygen and will die. As they decompose, bacteria will use up even more oxygen from the water.

Suspended solids can clog fish gills, reduce their growth rates, decrease their resistance to disease, and prevent proper egg and larval development. As particles of silt, clay, and other organic materials settle to the bottom, they can suffocate newly hatched larvae. Settling sediments can fill in spaces between rocks which could have been used by aquatic organisms for homes.

Test Procedure

Use the turbidity test kit provided by Lamotte (or other supplier) to determine turbidity level in Jackson Turbidity Units (JTU). Follow the instructions provided with the kit. Please note if you use a Secchi disk instead and record your results in centimeters (cm).

What to Expect

A turbidity reading of 0-10 JTU is considered normal.

References