Turbid water will be incredibly murky, and typically easy to spot with the naked eye. If the water outside of your barriers is becoming the same shade of brown as the insides, there may be a problem. However, if you want to ensure your project is meeting very specific standards or requirements, there are tools that you can use in order to measure turbidity: a nephelometer.
A curtain with tears or rips, or one that has become dislodged or unanchored, is going to have a much harder time catching silt. Moving fabric or cables that has been torn free may be a source of turbidity itself. Otherwise, your curtain may not be strong or flexible enough to withstand currents, waves, etc. A curtain that has been shoved out of position or submerged underwater will be unable to function properly.
