Common Chemical Tests
Turbidity refers to the dissolved solids in the water, which you can see. Cloudy water is said to have a high turbidity level. Common causes of turbidity are erosion, runoff, waste discharge and algal growth. Turbidity is usually determined using a black and white disk, lowered into the water until the white is no longer visible. The depth at which the disk can no longer be seen is indicative of the turbidity.
tests, including and/or in addition to those described above, may be appropriate
for the watershed in your area. The indicators the were chosen as points of
study while making your monitoring plan are a good way to decide what tests need
to be performed.
Water Quality Monitoring: Turbidity from Friends of Five Creeks
USGS Water Resources--Office of Water Quality National Field Manual Chapter 6.7 Turbidity (pdf)