First understand the Dictionary definition of Turbid. Then change it to Turbidity: "I cannot see the bottom of the Stream because of the Turbidity of the water." {Short Answer}.
Use it's (with the apostrophe) only when you mean "it is" or "it has." For example: It's time to go. (It is time to go.)It's been a long time. (It has been a long time.) Use its (without the...
Very roughly....
A train is 'due' when it is about to arrive.
Money is 'due' when it is owing to someone.
In (almost) all other cases, 'do' is the verb for an action "Did you do your...