The thrill of High Water can be quite exhilarating. In an effort to enjoy the thrill and not the spill of High Water Rafting, I always remind myself of these 5 things.
1) Remember to have people lean in when dropping into a large hole. I like to have 
paddlers drop to one knee to avoid getting tossed around and to lower the center of gravity in the boat. Remind them to quickly sit up and reach for down stream water even if still on one knee as you exit the hole. I have used this technique over the last 20 years of guiding on the Upper Animas River out of Silverton, CO, one of Colorado’s most difficult sections.
2) Things happen fast, so start your moves early. Many a boater has had a surprise when they start their move around something, such as a rock or a whitewater hole, to find they have started too late! Be particularly careful on high gradient rivers, like on the San Miguel River trip out of Telluride, CO.
3) Prepare for the COLD! The water is very cold when it is high and proper thermo gear is critical. This cannot be overemphasized; you must dress for the swim, even if it is 80+ degrees. This is especially true on rivers cascading out of the San Juan National Forest in Colorado.
4) Portage. Do not be afraid to skip a rapid you usually run. Mild to Wild always portages Eye of the Needle rapid on Piedra River rafting trips at high water. Although the rapid may often be successfully navigated in high water, the consequences are so magnified, the risk/reward ratio comes out of balance. Scouting makes for not only good company policy, but also good boating policy.
5) Swim aggressively for shore if you fall out and find yourself away from the boat or the boat is upside down; forget the paddles (or any other gear) it can all be replaced. Roll over with your head up stream and swim like Michael Phelps for the shore so you can crawl out of the river. High water makes it even more important that you do not try to stand up until the water is well below your knees.
Have fun, be safe and boat for the next trip.
See you out there.
Alex Mickel
Guiding Rivers since 1989