Bad trends in Utah between this and the ruling against the USFS & State a few years back from the bear attack.
Low head dams are scary and dangerous for boating. That said, a quick google search and use of the Wayback Machine
does show a lack of information about the feature before the 2010 incident. There is no mention of the low head dam on the American Whitewater description until someone updated with a warning after the death and even then its a secondary component of the page. I am all for boater accountability but there does seem to be some fault on the municipalities with this one. They had a plan in place since 2008 to work out river trails and signing but failed to fund it properly enough to make safety changes.
Hope they find the $$ to prevent future deaths and make the run safer. Low head dams and diversions ultimately need to have boater channels and not just signs, overgrown ones at that.