What was the Oneonta Aerator from 1950s?

This post card, from the 1950s identifies this as "THE AERATOR AT THE ONEONTA, NY RESERVOIR."  My question is....

"What the heck is this?"

Look at  the photograph.  The area is roped off so you were allowed to watch this exciting water action.  Notice the two young women (in dresses!) marveling at the sight. Now, we all know where the Oneonta Reservoir is.  But where was this "aerator?"  Is it gone?  Did it do this Niagara-thing regularly?  Did tourists really go up East Street to watch this?  When was it taken down?

All of these questions from one simple 60-year old post card.

Anybody got a clue?