Some suggestions for herons that
have worked for pond keepers are

- motion activated sprinker systems, setting two
in a cross pattern
- electric shock fence barriers
- a series of wires strung above the pond making it hard to land
- netting the pond

What works for you will depend on how your pond is situated and how
your yard is set up.Herons need some landing room as they have a wide
wing span but they can land away from the pond and walk in. They like
to stand and watch for their prey to swim by but they can float around
like a duck if needed.

For my pond having two labradors on guard duty took care of my heron
visitor. But it also helped that I was home and able to eject the dogs
from the sofa and out the door to do their duty ;-)

kathy