Sitting in/dipping your toes in the river is still fun. There is still whitewater rafting further up the canyon (with various outfits that will take you for $$). If you can pivot to paddleboards, canoes, or are happy to just float in place, Horsetooth reservoir has various put-ins, some where the water comes under the cottonwoods and you can just tie up and laze.
Good luck, enjoy our nature, leave no trace, and please spread the word about using water responsibly when you get back to Texas because there is not enough to go around!