I have to say that, if anything the water looks like a pool of liquid metal/mercury, which is to say, it's a pretty cool looking effect for something other than the murky water you're going for.
And I have to second the Donkey Kong Country 2 water effect. I, however, don't think its effect will match the view/perspective you're going for, so I suggest using the dark color against the bottom of the waves, with a few simple rays of very subdued light appearing to fade in/out with the passing waves to simulate the murkiness of the water. As for the middle and bottom respectively, I would suggest using a solid color to indicate the water, and then for the bottom, just some *subtle* shifts up/down of perhaps the same dark color simulating some weak up/down motion (not the flowing pattern you've got there, which looks like a roaring riverbed with stringy kelp or something flowing), or just some plants/grass/algae shifting back and forth very slightly or something to keep it lively.