Approvals sequence
Because the two approvals answer different questions, and only one of them is about the thing being built. An assessment under Part IV of the Environmental Protection Act 1986 decides whether a proposal may be implemented and subject to what conditions. Construction of a prescribed premises is authorised separately, under Part V, by a works approval — and section 54 requires that application to be supported by such plans, specifications and other documents and information as the CEO requires. A concept does not satisfy that; a design does. There is a second half to this that changed in 2024 and is still widely misstated. It used to be broadly true that other approvals were held up until the EPA assessment concluded. Section 41 now restrains only a prescribed class of restricted decisions, and a Part V works approval is not one of them.
A Ministerial Statement decides implementation, not construction
Part IV is an impact assessment process. It ends, where a proposal has been assessed, with an authority served under section 45(12) — the instrument published as a Ministerial Statement, carrying the conditions to which implementation is subject.
What that instrument settles is whether the proposal may be implemented and on what terms. It does not authorise the physical works. Section 52 of the same Act is unambiguous about where that authority comes from: an occupier who carries out work causing premises to become, or to become capable of being, prescribed premises commits an offence unless the work is done in accordance with a works approval.
So the two instruments are not sequential versions of one permission. They are different permissions, granted by different decision-makers, against different tests. Holding one and not the other is not being most of the way there.
Part V is where the design gets read
The distinction that matters commercially is what each process reads. Part IV assessment is conducted against environmental factors and their objectives — for water, the Inland Waters factor, whose objective is to maintain the hydrological regimes and quality of groundwater and surface water so that environmental values are protected. The evidence is predictive: what the proposal will do to the receiving environment, and whether the residual impact is acceptable.
A works approval is assessed against an object. Section 54 asks for plans and specifications. The department is deciding whether the described structure performs as described, which means levels, capacities, dimensions and design events rather than outcomes and objectives.
A proponent who arrives at Part V with an environmental case and no engineering case has not arrived with a weaker version of the right document. They have arrived with a different document.
What the 2024 amendments changed, and what they left alone
Section 41 restrains decision-making authorities while a proposal is in front of the Authority. A decision-making authority that has referred a proposal, or been required to refer one, is not to make a decision that could have the effect of causing or allowing the proposal to be implemented until either it is informed the Authority will not assess the proposal, or an authority is served on it under section 45(12).
The 2024 reforms did not remove that restraint. They narrowed what it attaches to. Section 41 now carries a definition — restricted decision means a decision of a prescribed class — and the prohibition operates by reference to restricted decisions rather than to decisions generally. Everything outside the prescribed class falls outside the hold.
The prescribed class is set out in Part 2B of the Environmental Protection Regulations 1987, inserted by the Environmental Protection Amendment Regulations (No. 4) 2024. It contains two things. Regulation 3G captures decisions relating to a petroleum activity involving hydraulic fracturing, made under listed provisions of the petroleum regulations. Regulation 3H captures decisions made under planning legislation, which is itself a defined list — the Planning and Development Act 2005, the Metropolitan Redevelopment Authority Act 2011, the Swan Valley Planning Act 2020, the Port Authorities Act 1999 and others, together with related decisions of the State Administrative Tribunal.
A works approval is not a restricted decision
Read the two lists against each other and the conclusion is plain rather than clever. A works approval is granted by the Department of Water and Environmental Regulation under Part V of the Environmental Protection Act 1986. It is not a decision under planning legislation and it is not a petroleum activity involving hydraulic fracturing. It is in neither prescribed class.
The practical consequence is that a Part V works approval can be assessed and decided while a Part IV assessment is still running. The older advice — that nothing else moves until the Ministerial Statement issues — was a reasonable description of the position before the amendments and is no longer an accurate description of the position now.
That is a change in what is permitted, not a change in what is prudent. Parallel processing removes a legal bar. It does not remove the risk that a works approval assessed against one design has to be revisited when Part IV conditions land on a different one.
Parallel processing only helps a proponent who can supply both cases at once
The reform transfers the constraint from the statute to the applicant. Where the two processes may now run together, the limiting factor is whether the proponent has the evidence to feed both — and the two want the same underlying work expressed two different ways.
The receiving environment characterisation, the site water balance and the predicted discharge behaviour are inputs to the Part IV case. The storage volumes, design events, freeboard, spillway capacity and drainage capacity in the Part V case are the same hydrology, resolved further. Built once to the standard of the harder reader, one body of work serves both. Built to the standard of whichever process is in front of the proponent at the time, it serves one and gets rebuilt for the other.
This is where the time is actually available, and it is available only in advance. A proponent who reaches the end of Part IV and then starts the engineering has not used the parallel pathway at all; they have simply been permitted to and declined.
What gets rebuilt when the sequence runs backwards
The rework is rarely the modelling itself. It is the reconciliation. A storage sized volumetrically for a referral figure has to be resolved into a structure with a depth, a freeboard, a spillway and access, and that structure has a plan area which may not match the area drawn on the figure. Where the cleared footprint has been fixed by a Part IV condition, the mismatch is not a design problem. It is an approvals problem, and reopening it is slower than the design work that caused it.
The cheapest version of this article is one sentence. The order in which the approvals are granted has become more flexible; the order in which the evidence has to exist has not moved at all.