We are planning a stay at Fishing Haven CP near Yamba, and its pet friendly. Haven't been yet, so can't tell you more than that. www.fishinghaven.com.au Rosie
I went to Yamba and couldn't find Fishing Haven CP, I guess I didn't try hard enough. I've found that around the Ballina area that most of the parks are not that dog friendly. Sure there are some small parks but the better ones seem to be no dogs. It's a shame because it is a really nice area.
I think there is one at South Ballina, a little bit off the beaten track. I always spend a night a New Italy RA and explore through the day.
Fishing Haven is lovely - we stayed there in Dec 2010, it's not actually in Yamba (on Palmers Island) - it's quite, the owners were really nice, a number of permanent residents (no problems though) and the tourist sites are right on the river. I also found Yamba Waters http://www.yambawaters.com.au/ haven't been there but it might be worth a try! The one at South Ballina is Ballina Beach Holiday Park http://www.ballinabeachpark.com.au/location.php also, haven't been there, but took a drive that way and it looked nice. They say "We are the most pet friendly park in Australia" - would be interested to know if that is true! If you are looking a bit further north Ferry Reserve at Brunswick Heads http://www.nchp.com.au/our_parks/ferry_reserve_holiday_park/ is very nice - they have a couple of other pet friendly parks in their group also. We have also stayed at Mullumbimby Rugby League Club http://www.mullumbimbygiants.com/?D=37 the facilities are a bit old and tattered, but the people are friendly, powered sites are right on the river and it's very pet friendly, lots of fields for the fur kids to play on - just follow the usual rules.