Turbid is a formal word that has several meanings having to do with literal or figurative muddiness or cloudiness. It’s most often used literally to describe water that is thick or opaque with stirred-up sediment, as in “the river’s turbid waters”; similarly, turbid air is smoky or misty. In figurative use, turbid describes things that lack clarity, as in “efforts to clear my turbid mind.”
The group decided to forgo stopping at the swimming hole on their hike because of its turbid waters.