Starved Rock State Park is in Utica, Illinois. The park is about 2 hours away from Chicago.
My favorite times to visit, in order, are Autumn, Winter, and Spring. Summer is too crowded and the waterfall flows are typically minimum.
This image is not from this year so I cannot say for sure what it might look like right now. The water flows this year have been excellent but the alternating hot and cold spells might not be sufficient to build a great frozen waterfall.
I was fortunate to have this woman and her two dogs show up when I was there. I asked to stand still and she did. I like the pink booties on one of her dogs.