(West side of Spirit of St. Louis Airport access across Chesterfield levee along Olive Street Road). Best levels: 20.0' to 23.5'; and 26' - 26.5' on St. Charles gauge of Missouri River. From 18.5' to 20' it is pretty tame and suitable for low intermediates. Normally runnable March-April during typical Spring flooding or for short periods after abnormally heavy rainfall upstream. River-wide keeper hole at 23.5- 26 FEET - easily visualized by paddlers who understand hydraulic dynamics!!!!! Strong Big Water Class III experiences at other levels below these primary and secondary wave-holes at the top of the rapids. Very poor water quality when runnable because it is essentially a flooded river experience.
The holes on river right are usually friendlier than those on river left. River-right most hole is called Freight Train, because at normally safe levels it continually chugs the paddler toward the obvious retendo-quality"out" further left. Normally, Freight Train is most easily entered from the extreme-most river-right point. However, the upstream side is extremely shallow so one needs to make sure one is precise in keeping one's upstream edge up. Else one might have an encounter of the wrong type with concrete, rock, or rebarb.
Immediately as one comes out of Freight Train is a secondary hole called Big Trash Can. Big Trash Can is never a keeper but is chaotic enough that it is difficult to surf it without getting stuffed upside down against the whirlpool-eddy lines below making rolling a challenge for those with only a one-side roll. Becoming ambidextrous is a virtue in retendo, after all.
David Klein has christened the river-left hole in back of the first hole/wave "Oscar the Trashcan". ( Upper left corner of picture below.) This is often a playable hole but the steep upper side can make it extremely difficult to exit - even upside down - as kayaks tend to recycle and there is very little pile on the downstream side for bracing. The primary wave-hole in front of Oscar is not the problem. Oscar is the secondary hole created by the first , very playable wave-hole, at most levels below 23.5 and above 25.5 feet.
Occasionally, at roughly 26.3 to 26.5 feet on the St. Charles Gauge, Howell Island provides the Perfect Glass Wave. This is a primary glass wave about 10 feet high and 100 feet wide that has no secondary hole problems and which has been surfed by boaters switching sides by one paddler charging forward while the other drops back to the top of the wave for making cool switches. However, I have never seen this wave except under flood conditions where freight trains of huge trees are coming down the middle of the channel, so one needs to have the boat control for moving left or right 10 to 15 feet to avoid becoming part of what may be one of the world's few moving strainers.