Rural water
In Western Australia a landholder may generally build a dam that captures runoff without a licence, provided four conditions hold: the water is not stored on a watercourse or wetland; there is no sensible reduction in the volume of any watercourse or wetland; there are no significant environmental effects; and local by-laws are met. Inside a proclaimed surface water area, taking water requires a licence. And in every case, interfering with the bed and banks of a watercourse is a separate approval from taking the water — two approvals, not one.
Proclaimed and unproclaimed
Most of Western Australia’s groundwater and the surface water resources under high demand are proclaimed under the Rights in Water and Irrigation Act 1914. Inside a proclaimed area it is an offence to take surface water or groundwater without a licence or a valid exemption. Outside one, riparian rights extend to taking water provided the flow in the watercourse or the amount of water in the wetland is not sensibly diminished.
In the Great Southern this matters more than the map suggests. The Albany groundwater area was proclaimed in 1973 and extended in 1975 and 1979, covering about 280 square kilometres of the coastal strip, and abstracting groundwater there requires a licence. The Albany hinterland — roughly 1,200 square kilometres inland toward Redmond, Napier and Manypeaks — remains unproclaimed. For surface water, the Two Peoples Bay surface water area including Angove Creek was proclaimed in 1997, and Bolganup Creek in the Porongurup Range is a proclaimed surface water area. Much of the surrounding agricultural country is not proclaimed for either.
The exemptions, and their edges
On a proclaimed surface water resource, a landowner whose land adjoins a watercourse or wetland may take water without a licence for domestic use, for stock watering that is not intensive, and to irrigate a garden of up to two hectares connected to a dwelling. The riparian exemption does not extend to the bed and banks: a permit is still required in a proclaimed area to construct anything that interferes with them.
For groundwater, no licence is needed to construct a well or take water where the development is in the water table aquifer and the use is domestic — household use, watering a lawn or garden under 0.2 hectares, firefighting, or non-intensive stock watering. Artesian wells require a licence anywhere in the state.
Dewatering has its own narrow exemption: water table aquifer, construction purpose, no raw material extraction, under 10 litres per second, under 30 consecutive days, and a total of no more than 25,000 kilolitres. Exceed any one of those and it becomes a licensed take.
What "no sensible reduction" actually asks
The farm dam exemption turns on a phrase that reads as legal boilerplate and is in fact a hydrological question with a number attached. "No sensible reduction in the volume of any watercourse or wetland" is a comparison between what a catchment yields and what the dam intercepts, over the years that matter rather than the average year.
Answering it properly means establishing the contributing catchment area, the dam’s capacity and the storage-to-yield ratio, the proportion of annual runoff intercepted, and the effect on downstream flow in dry and wet sequences. On a small paddock dam that is a short exercise. On a larger storage, on a catchment already carrying several dams, or upstream of a wetland with an environmental value attached, it is not — and it is the question a licensing assessment will ask if it asks anything.
Where a licence application is required, the department may seek reports on water resource investigations, hydrological monitoring reports and an operating strategy. Those are the documents the hydrological work produces.
Dam safety in WA is not what people assume
Western Australia has no dam safety legislation. There is no statutory "referable dam" category equivalent to the Queensland construct, and many shires require no approval at all to construct a private dam — including dams larger than some public water supply storages. ANCOLD consequence categories apply here as industry guidance, not as law.
That absence is not a reason to skip the assessment; it is a reason the assessment is the owner’s to commission. Where a dam sits above a road, a dwelling or a downstream neighbour, a failure impact assessment is the difference between an engineered risk and an unexamined one — and some insurers require structures covered by their policies to be built and maintained to the relevant Australian Standards regardless of what the shire asks for.