Answer: It depends on what's in it and what's over it, which varies seasonally, not to mention in response to weather, precipitation, and how much sediment gets stirred up depending on the force of the stream in the watercourse. The most common hue I would say is comparable to the appearance of cheap olives taken from a can. It's hard to find the bayou waters blue. On rare occasions, however, the Bayou surface is actually multi-chromatic: Behold - Here is the proof: Blue, white, and green.
And this is how it looked further up in mid-November under a canopy of trees.
So what would that be? Olive-green? Save for the spots illuminated by setting sun?