Yes, fresh water river front, 400 or 500 metres from the house, & the dam half way down to the river. Perhaps our red belly blacks have yellow bellies. These were venomous to kill a dog in just one minute.

We have lots of trees in a windbreak south & west of the house, a small orchard & many tree plantings around the house paddock, so lots of green tree snakes. One quite large one for a tree snake lives in the hay shed.

We had a couple of very nasty aggressive ones a few years back. Sage green with blue spots. Large sort of triangular body, with a small head so probably venomous. One threatened my daughter when she went to open the gate to the saddling enclosure. We showed it to the snake expert at Canungra army base. He had never seen one or seen it described. He thought snakes might be cross breeding as he had seen a few he could not recognise recently.

//Perhaps our red belly blacks have yellow bellies.//

Colour variation aside, do your culprits resemble these snakes:

http://en.wikipedia.org/wiki/Red-bellied_black_snake

Or these ones:

http://en.wikipedia.org/wiki/Dendrelaphis_punctulatus

Hasbeen thought last night it had to be a redback
Know some yellow appears in some
Water here too, dam, but not sure about interbreeding, know it has been said it happens

Definitely not a tree snake. Not much like the first either, & most definitely have fangs, & kill very quickly.

They are mostly over 2.5m, & many are well over 3 m when around the house paddock. We are very careful when moving stacks of timber roofing iron & the bath tubs we use as water troughs for the horses.

//Definitely not a tree snake. Not much like the first either, & most definitely have fangs, & kill very quickly.

They are mostly over 2.5m, & many are well over 3 m//

Well, I'm stumped. I can't think of an elapid snake that grows that big and matches the colouration. I recommend you take some photos and get in touch with ophidologist.

Good advice Tony Lavis, once kept snakes and mixed with others who did
Wandered around the Australian Reptile park often ,no idea what it is
Story in Sydney press told of snake catcher removing a brown from a bed in Brisbane
Here red belly,s grow to huge sizes, unlike the southern highland , there the browns are huge
Shame more do not know red belly,s kill browns
Tony Lavis any thoughts on cross breeding?
Heard about it but never saw it