https://fpos.fcnsw.com.au/A-Guide-to-Fossicking-in-New-South-Wales.PDF
"
On land or waters that are not subject to native title, fossicking is not restricted to hand held
implements, but power-operated equipment cannot be used for the purpose of surface disturbance,
excavation or processing."
Mining Regulation 2010 under the Mining Act 1992
clause 12 Fossicking
(1) Any soil, rock or other material that is disturbed in the course of work
carried out for the purpose of fossicking for minerals must:
(a) be removed and stockpiled separately, and
(b) after completion of the work, be replaced in order to reconstruct
the original soil profile.
(2) A person must not carry out work that includes any of the following
activities for the purpose of fossicking:
(a) the use of any equipment other than hand-held implements on
any land or waters that is subject to native title,
(b) the excavation or clearing of any land or waters that is subject to
native title,
(c) the use of power-operated equipment for the purpose of surface
disturbance, excavation or processing on any land,
(d) the use of explosives on any land,
(e) the damage or removal of any bushrock,
(f) the removal of more than the prescribed amount of material from
any land during any single period of 48 hours,
(g) the disturbance of more than 1 cubic metre of any soil, rock or
other material during any single period of 48 hours.
In this clause power-operated equipment means any equipment powered by
mechanical or electrical means.
The problem is highbankers are not defined in the current legislation, the prospectors argument is that obviously the water pump is not being used to disturb or excavate (opposed to dredging) it is used to transfer water from point A to point B and the highbanker is not mechanically (or thankfully electrically) driven its simply a semi fluidised bed/gravity trap
There are no issues with current legislation for using water in this way. The grey area however is the wording "processing" and we can argue that placer gold is already in the alluvial deposit, we are not extracting by mechanical means the gold from gold bearing ore. That we are just washing away other less desirable materials with the use of the legally obtained water and gravity, which I assume is also still free to use
The Fisheries Officers I ran into could not see that argument and insisted I was dredging. Their main concern being wash/turbidity caused by the highbanker, even though I had allowed a good 5m for silt/mud to be filtered or settle. The tail it produced was no longer than 10m and cleared fully in very little time after I had shut everything down. So 300m downstream in Qld, is determined excessive, and maybe rightfully so as I doubt there is a prospectors sluice or highbanker that could produce such an amount of turbidity from tailings unless it was actual mining plant like "Monster Red" but in NSW there is no determination and its left up to the discretion of those given the power to uphold the regulation.
If I was given a fine, I would have had to tread carefully because at the current time no one has been prosecuted for highbanking in NSW and for the sake of every other prospectors in NSW I would certainly not like to see myself on the losing side of a court case that sets precedent for all of us.
It works both ways though as this is the reason no one has yet been prosecuted because if the government agencies (or people a part of them) opposed to the hobby we love, don't yet have a strong enough case to effectively shutdown highbanking. A court case in favour of the humble, rule following, hobbyist prospector sets precedent and possibly puts an end to the stick waving of some select public servants and politicians.
Unfortunately for us at the current state of wording it all depends on a persons interpretation of the act and if they are in a good or bad mood!