Why did the heron cross the river?

When we parked by the river this morning, on our way to the pool, the heron - which habitually stands on the far side of the river, directly below where the building work is in progress (this may explain why we've seen it less often this summer) - was beside the clump of reeds, just by the steps up tp the footbridge, within a few metres of us. We watched as it stood, then took off unhurriedly and crossed the river with two or three beats of its wings, back to its usual place.

I've never seen a heron from so close before.