It was years ago on a commercial trip (I was just geeting into river running then), but I will do the best with remembering.
I recall about 4000 cfs (1st week in June) being the flow. Nothing seemed to hard with the exception of Hells Half Mile. The big rock at the entrance to the rapid was covered and the rafts went right over the top. About an 8' to 12' wave, but nothing to difficult as far as manuvering went. After picking up the Yampa, the flow was 19,000 cfs. Nothing hard below echo park, but it only took 45 minutes to run Split Mountain Canyon at this flow!