pumphouse to state bridge - so, Class III? Why don't you consider putting in on the South Platte at Deckers and running that all the way down through Waterton Canyon.
Shoshone flows are visible by clicking on "flows" and looking at the Colorado Drainage. It's fun but quite a drive. Of course, with Waterton, there's the walk. I'd rather walk out Waterton than drive to Shoshone...
Will probably have a group going to the South Platte on Saturday to do the Deckers run with some newbies, then finish off with Waterton for fun.
Lots of people still going down to the Ark, ya know. Brown's.