The award is given to the author, or authors, of that paper which is judged to be of superior merit, dealing with a problem of flowing water, either in theory or practice. Preferably, the award is given to a paper that is not otherwise recognized by receiving another Society prize. See the list of winners at: https://www.asce.org/career-growth/awards-and-honors/karl-emil-hilgard-hydraulic-prize/karl-emil-hilgard-hydraulic-prize-past-award-winners