Bill Taggert of Taggert Engineering in Denver has been involved with some hydraulic engineering advancements to the design of boater safe drops in the Denver area, and was also involved with the original design of Confluence Park in Denver. He owns Taggert Engineering, and I think has had some papers published on the hydraulic design of boater safe drops. He may share some experiences of designing Confluence, truly one of the first parks if not THE first.
Also, Wright Water Engineers (or WWE) in Denver and Glenwood has done some work on boater safe drops. Some of their staff have published papers on the topic, but I don't know who specifically.
Also, you might simply ask Gary Lacy for the names of some other current designers, since you just want to gather info for a paper. He should know who his competition is.
Phillip Bowman, P.E.