A buoy or system of buoys would be the best option here. Buoys placed in the center of the channel would allow the strength of the current to be seen from both above and below the surface. These could be installed quickly and inexpensively and would allow everyone the ability to see the conditions both in and out of the water. Once installed a rating system could be used to determine acceptable and safe limits based on the movements of these buoys. Hopefully this is something that is addressed quickly for the safety of all involved.

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