Turbidity is an optical characteristic of water; it is its ability to diffuse or absorb incident light. Turbidity is therefore one of the factors in the colour of water.
Turbidity is due to the presence in the water of suspended inorganic or organic living or detrital particles. Thus, the greater the amount of phytoplankton biomass or sedimentary particles in the water, the more turbid it is.
Turbidity affects the penetration of visible and ultraviolet light into water and hence photosynthesis and the growth of bacteria. The colour of water also affects its temperature and therefore its oxygen content, its evaporation and its salinity.
The brown colour of this water is due to its turbidity. © F. Lamiot, Wikimedia CC by-sa 3.0