Took a closer look at the weed - what look like lighter colored stems are apparently leaves wrapped around each other. These seem to start at the base of the root area. The upper part of the leave as it flattens out has a vein down the center and several smaller lines or veins parallel to it. The upper part of the leave that is flat is more red in color and it seems to lay flat near the surface of the water.
Could this be either wild celery or ell grass?? I don't see any flowers or seeds or creeping rhizomes. So far longest leaves are only about a foot long.