This is the best resource for all the river surfing spots in Colorado and more. Jake Voss is the author and he knows his shit. Period!
Start with his Wave Guide by clicking here: https://endlesswaves.net/waves/
Jake recently moved up to the mountains to feed his addiction of backcountry skiing, but when you figure out who he is at any river wave, give Jake mega respects for all the information he provides about river surfing in Colorado.
The Denver Surf Report 