Fox (Illinois R. trib.) - D) Yorkville: Marge Cline Whitewater Course (PnP) (IL)
Perhaps optimum playable flows.
On river-right of the island is "play wave". Experienced playboaters may be able to throw a loop here, but it takes some effort to find the sweet spot. At many flows, the 'pocket' tends to be too narrow/tight for most boaters to be able to get sideways (to side-surf) or to spin.