
I’ve seen a few ~aesthetic~ photos of rock stacks in rivers recently and this is just a reminder that you are destroying habitat when you move rocks around in rivers and streams.
In addition to dragonfly nymphs, rocky river beds are home to lots of other larval invertebrates like damselflies, mayflies, water beetles, caddisflies, stoneflies, and a bunch of dipterans. Not to mention lots of fish and amphibians!
Plus large scale rock stacking can change the flow of a stream and lead to increased erosion.
Anyway dragonfly for admiration:

Calico pennant by nbdragonflyguy










