Easy there.
I agree that the images (grainy and blurry as they may be) fit with
Ostrya virginiana - Hophornbeam. I've grown and managed this species in a broad array of landscapes.
While riparian zones are not where I would plant this species (better choice is the similar appearing
Carpinus caroliniana), the Hophornbeam certainly would have no compunction against growing there. Creek corridors all over central KY have this species evident, though usually not in the inundation zone. Some pictures which showed the whole plant and its growing context would resolve this question. I suspect that a closed canopy overhead and incomplete fertilization of the flower led to abbreviated seed cluster in this instance.
Here are some images of
Ostrya virginiana that I know and love...