Midpoint?

Jamison Square Park fountains at twilight.

I think the fountains went on May 1, but I've been too busy to notice. Tonight, blipless, I went for a walk at twilight and watched the water rush in at the ends, then in the middle, then all together, then stop with a full pool, then start again, then drain, then begin all over again. That may not be the precise pattern, but you get the idea.

So which phase is the midpoint?
If you know, you'll be sure to make a splash.

CHALLENGES

Anniemay+Mollymay
Midpoint

DDW: Where I Live
I live at Jamison Square.