EPA approvals
Inland Waters is one of the environmental factors the Environmental Protection Authority uses to assess proposals in Western Australia. The EPA defines it as the occurrence, distribution, connectivity, movement and quantity of inland water — the hydrological regimes — together with its chemical, physical, biological and aesthetic characteristics, which is the quality. One factor covers groundwater and surface water together: superficial and confined aquifers, waterways, wetlands and estuaries, including systems that flow only part of the year or only occasionally, and including parts of a waterway that have been artificially modified. The objective is a single sentence, and it is the test the whole assessment is written against — to maintain the hydrological regimes and quality of groundwater and surface water so that environmental values are protected.
Two old factors, one current one
The current guideline is dated 29 June 2018, and it replaced two documents at once: the 2016 Environmental Factor Guideline for Hydrological Processes, and the 2016 Environmental Factor Guideline for Inland Waters Environmental Quality. Water quantity and water quality used to be assessed as separate factors. They are now one.
That is more than a filing change. The reason the EPA gives for the objective is the fundamental link between the hydrological regimes and the water quality of inland waters, and the environmental values supported by or dependent on them — so an assessment that answers one half cleanly and treats the other as somebody else’s section is answering half a factor. A report structured against either 2016 guideline is structured against a document that no longer exists.
What counts as inland water is broader than most people assume
Inland waters include groundwater — superficial and confined aquifers — and surface water: waterways, wetlands and estuaries. The definition of a waterway is where sites get caught. The EPA defines it as any river, creek, stream or brook, including its floodplain and estuary or inlet, and it expressly includes systems that flow permanently, for part of the year, or occasionally, along with parts of the waterway that have been artificially modified.
Three consequences follow from that one sentence. A channel that runs for a few weeks after winter rain is a waterway. A creek that was straightened, piped or realigned decades ago is still a waterway. And the floodplain is part of the waterway rather than a separate thing beside it — which is why on a great many sites the flood evidence and the inland waters evidence turn out to be the same body of work.
The objective has two halves, and the second one is the one that bites
Maintaining regimes and quality is the first half. The second — so that environmental values are protected — is what the significance argument actually turns on. Environmental value is defined under the Environmental Protection Act 1986 as a beneficial use or an ecosystem health condition, and the guideline sets out what the EPA is focused on under each.
On ecosystem health, the significant ecosystems include Ramsar wetlands; conservation category and resource enhancement management wetlands as mapped in the Geomorphic Wetlands of the Swan Coastal Plain dataset; wetlands listed in the Directory of Important Wetlands in Australia; wetlands protected by an Environmental Protection Policy under Part III of the Act; wild rivers; wetland types poorly represented in the conservation reserve system; springs and pools, particularly in arid areas; ecosystems supporting significant flora, vegetation and fauna, including migratory waterbirds, bats and subterranean fauna; saline lakes, estuaries and near shore ecosystems reliant on groundwater or surface water inputs; and downstream marine ecosystems.
On beneficial uses it is drinking water supplies; significant current or potential supplies such as regional scale aquifers and fresh, high order surface water systems; supplies that underpin significant non-potable use and commercial activity; inland waters carrying high levels of active and passive recreation, including multiple use wetlands; and inland waters with significant cultural and aesthetic values.
Read that list against a specific site and the assessment question stops being abstract. It is not whether the proposal changes water. It is which of those values sits downstream, upgradient, or in the same aquifer — and what the change does to it.
What the EPA asks for when Inland Waters is a key factor
Where Inland Waters is identified as a preliminary key environmental factor, the guideline lists the information the EPA may require. Characterisation of the surface water and groundwater systems, including climatic influences on water availability and, where relevant, location, hydrology, water quality, catchment boundaries, geology, hydrogeology and connectivity, locally and regionally. A description of the environmental values those systems support. What water the proposal will use, and what else in the area uses it. How excess water is to be disposed of. Characterisation of the waste generated and the pathways for potential contamination, quantified through models where necessary.
Then the predictive half: modelling of abstraction and use on water regimes and other users, stated with its assumptions and uncertainties; predicted changes to surface and groundwater regimes; the consequences for downstream waters such as estuaries or the marine environment; predicted impacts on water dependent ecosystems; and an evaluation of the significance of direct, indirect and cumulative impacts in a local and regional context.
And the part left out most often. The guideline asks for the predicted outcome against the environmental objective, whether a significant residual impact is likely, and the adaptive management or contingency planning that applies if the predictions turn out to be wrong. The EPA states separately that it considers the level of confidence in predicting residual impacts, and the risk to environmental values should those predictions be incorrect. A model presented without its uncertainty is not answering that question — it is declining to.
Where the factor links to everything else
The EPA is explicit that changes to the quality or quantity of inland waters can affect flora and vegetation, terrestrial fauna, subterranean fauna, benthic communities and habitat, marine environmental quality, landforms, social surroundings and human health — and that while those impacts are considered under their own factors, Inland Waters is considered in concert with them in order to assess impacts on the integrity of the ecosystem as a whole.
The practical version: the hydrological evidence base is an input to several other factors’ assessments. Built once and built properly, it feeds all of them. Built narrowly to answer a single question, it gets rebuilt from scratch by somebody else for each of the others, and the versions disagree.
Which half of this a surface water practice covers
Inland Waters is one factor spanning two disciplines. Groundwater — aquifer behaviour, drawdown, movement of the seawater interface, aquifer recharge and injection, well integrity where a bore intercepts several aquifers — is hydrogeology. Surface water — catchment yield, flow regimes, flood behaviour, discharge to creeks and wetlands, drainage, erosion and sediment — is hydrology.
This practice is the surface water half, working as technical support to the environmental consultant running the assessment rather than as a competing approvals practice. Where a proposal needs both halves, that is two specialists on one factor, and the connectivity between them is part of the technical work rather than an administrative problem to be tidied up at the end.
There is a second boundary worth naming, and it sits after this one. Satisfying the Inland Waters factor is a Part IV outcome. Building the infrastructure that delivers it is authorised separately, under Part V, against a design rather than a prediction — which is a different document asking different questions of the same water.