This happened during a water skiing show in northeast Wisconsin. The woman was attempting a heal hold with 5 other girls on either side of her doing the same. As she was skiing, she hit a random wave and the handle of the rope slip up her leg to about the area behind her knee.
As she went down, the spotter in the boat attempted to release the rope from the boat, but failed to pull hard and quick enough. The woman was dragged roughly 15 feet before the rope slid back down her leg, tearing away her calf muscle from her bones.
Props to Best Gore member @enduring11 for the pics and story: