Good observation. Mid-lake weed beds will also give this color change. In the pothole lakes around Edmonton, the water is somewhat turbid making it a little harder to see these changes but in clearer waters (like the mountain lakes) one can see color change from many under water structures. Honestly, this is something I've taken for granted. Come spring, I?ll make a point to watch for color change closely and see what structures I can find that way.
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