What cause turbidity of water?

Turbidity is the measure of relative clarity of a liquid. It is an optical characteristic of water and is an expression of the amount of light that is scattered by material in the water when a light is shined through the water sample, the higher the intensity of scattered light, the higher the turbidity.

Materials that cause water to be turbid include clay, silt, finely divided inorganic and organic matter, algae, soluble colored organic compounds, and plankton and other microscopic organisms.

However, any watershed has multiple sources of the pollutants or physical features that can affect water clarity. These can be divided into natural or background, and human induced sources.

Natural sources can include erosion from upland, riparian, stream bank, and stream channel areas; however, this is difficult to measure due to agriculture and development activity.

Human activities can accelerate erosion Tannic acids often associated with peat and bog areas cause water to be colored resulting in turbidity. Algae that grow with nourishment from nutrients entering the stream through leaf decomposition or other naturally occurring decomposition processes can also be a source of turbidity. Stream channel movement can also release sediment.

Algae growth, waste discharge, sediments from erosion, phytoplankton, urban runoff and resuspended sediments from the bottom.