A point of clarification: In the quote above the Chutes are referred to as "Union Chutes", which is in error. We are not talking about the waves at Union street in Denver, but the rapid known as "The Chutes" on the S. fork S. Platte above the confluence and the Waterton run.
With regards to touching the banks: As stated above, in the state of Colorado private property includes the stream bed and banks. I am not familiar with the area myself, but I have been told that the Denver Water Board owns most of the property in that area. So if you put in, take out, scout, or even touch the banks you are trespassing on DWB property. There may also be other adjacent private property, as referred to by Lyle in his original post. Obviously, folks have been boating this section of the S. Platte, scouting, portaging, putting in, taking out, bashing rocks with their paddles, etc. for many years. It is also evident that the DWB and local enforcement agencies have chosen not to prosecute trespassing violations by boaters (above citation notwithstanding). No doubt all of the signs saying "Closed Waters" went up because DWB was concerned about the liability of swimmers killing themselves on DWB property. That seems like a reasonable concern to me. So here would be my advice (again, I haven't been there myself):
1) If possible, scout this rapid from the road before you do the run, or if you scout on the way down, perhaps there is a public property access point above DWB property that you can take out at and walk down the road to scout the rapid. If DWB property is the only choice, then take the time that you need to to scout and be safe, but no more. Realize that you could be cited for trespassing, but that has not historically been the case.
2) If you need to stop in the eddy that is marked as "Closed Waters" as a safety precaution or to pick up swimming kayakers, by all means do so. I am going to go out on a limb here and assume that any enforcement official who sees a swimming kayaker in the eddy would realize or be persuaded that said kayaker is not swimming there intentionally. It is not illegal to float in that eddy. However, it would be prudent to spend as little time in that eddy as possible.
3) Don't go jumping or seal launching off of the rocks!
4) If you have discussions with law enforcement officers, be courteous and explain to them that the Colorado Revised Statutes exempt kayaks and whitewater canoes from river closures (exceptions noted in CRS 33-13-111 notwithstanding).
5) If you are cited for trespassing while touching a rock in the stream bed or on the bank below the high water mark, shoot me an e-mail describing the situation. It is unlikely that we could do anything about it, but if by chance the case looks favorable and goes to court, we might be able to set legal precedent with regard to the trespassing statute. The CWWA does have a fund set aside (not large), in the event that such a case comes along.