This is not Paspalum dilatatum according to me (There is no Paspalum sp. item in the list...) - but one that looks very similar. Don't know but could it be Vasey grass? That would have biosecurity implications.
I think this is Eriochloa. Possibly Eriochloa pseudoacrotricha. It's worth taking this to the herbarium as there are only a few records from the ACT. It's a species from our west. Probably brought into the ACT as horse feed or on vehicles.
Thanks Matt - I think you are right on the money here. I have since looked at the CNM records and others - and they look pretty much as I saw it. Thanks - well done! Indeed, the grass grows in a disturbed area next to a swale drain. It caught my eye on Sunday as it was not quite looking like a "typical grass". It is close to a horse paddock - and it is likely that it could have come in with horse fodder. There are a few plants growing in the spot - I will dig one out tomorrow, bring it to the ANBG and report back once I have the identification. Cheers Christian.