Just looking at tides for the upcoming big swell this Sunday in West Oz (September 6th), but there's a big difference between the BOM and DPI's websites.
The BOM's website states (note: no tidal range, just times):
HIGH: 11:19 pm
LOW: 2:41 am
HIGH: 6:01 am
LOW: 3:07 pm
On the other hand, DPI's website states:
LOW: 1:40 am (1.08m)
HIGH: 3:00 pm (0.64m)
So in short, they both have a low tide in the morning (2:41am according to the BOM, 1:40am according to the DPI) but the big difference is the BOM has a high tide four hours later (6am) and then a 3:07pm low tide. Instead, the DPI has a slowly incoming tide all day with high at 3pm. The complete opposite!
Or.. am I just reading this all wrong?
Dunno what's going on - and I've previously approached the BOM about this specific anomaly at this location in the past - but I'll try to get a response from them.
Also worth pointing out that the DPI tides are actually produced by the BOM. Which makes it even more confusing (see here for the DPI's disclaimer, referencing the BOM).
BOM tides for Cowaramup are here.
Judging by the tides lately the first tide column is correct. The tides here are hard to work out for some reason so i can see why there has been a stuff up. By the way it seems to me your tides are correct on the surf report page.