I think they can lay all year round, hasn't the spawn got some form of antifreeze in it so can survive in frozen ponds, That's how they survive in the far north of Scotland when the season is shorter. we saw some last week on Bleaklow, it wasn't star jelly
I've seen this before but didn't know what it was.
If it was smallish it could have been a dipper, I've mistaken them until I've got a bit closer, similar habitat rocky cloughs/streams