What is the name of your state (only U.S. law)? MI
We were at a Michigan Waterpark yesterday, and while climbing the stairs to a waterslide, my child and myself both fell due to there being standing water on the steps up to the slide. I fell down only a couple steps and only received a few scrapes. My child fell down about 10 steps and has about 20 or so cuts on his leg, a cut on his hand and hit his head on the side bar for the stairs. After telling a lifeguard they pointed us to the tube rental building, the person there called for a medical personnel, he came and examined my son and determined he had no head injuries, and bandaged him up decently.
A couple other things to consider, the slides above the stairs are dripping water onto the steps and platforms on the stairs on the way up. Also I do not recall seeing any sign saying "caution slippery surface" or anything to that effect.