Update:
Stack wave has gotten so high it's almost flushy but still great for getting used to front surfing but the hole further up the weir is working and deep enough for quite a few moves. I saw Mark Coleman in his custom C1 playboat styling it on Sunday.
Right hand side of the big A has a nice hole but it keeps you very close to the weir wall so that it's hard to get out of and if you flip you need to tuck up quick.
Slane castle weir is also working as a wave and hole but has a few issues. The first being the hole on river right is very retentive and unless you capsize or are good at working your way to the end of a hole you will stay in it. Far river right is good for flat spins, our instructor was able to spin his WW mamba without having a set of paddles in his hands. It's just deep enough that you might get your paddles scrapped on bottom if you're holding them at a weird angle. There is a nice eddy to enter the hole from. And lastly, a few hundred meters downstream there are trees on river right that stretch a third of the way across the river, meaning basically don't have a group of people who are going to swim a good bit unless their are people to rescue them.
Also this video shows Slane weir on sunday and after looking at it, river left might be good to play in as well.
The water quality isn't ideal at the moment as a lot of stuff has been dragged up off the river bed but it's still better than the Liffey.
Lastly, I know it's obvious but don't hit the middle of the big A. There's a huge undercut which for a big hole that shouldn't be messed with.
I think that's pretty descriptive eh?
And here's another level gauge, click on a time to see the level in cm