Walter, I have one control site already marked out specially for you and Trev,  "The knoll".  Tide charts will be included in the Course Setters Notes.

In most places downstream of the dam you will have no trouble knowing you are getting close to the Gwydir.
Just listen!

We do too, so the map will show places like this that you will be able to use for shelter if needed.

There are some quiet stretches.

Now if this was an orienteering event ...