Updated SAII guidelines increases pressure for strong biodiversity impact assessments for NSW developers

The New South Wales Government released updated ‘Serious and Irreversible Impacts’ (SAII) guidance in May this year. SAII is a critical aspect of the Biodiversity Development Assessment Report (BDAR) and broader Environmental Impact Statements (EIS) that developers must prepare for their projects, and these new updates significantly tighten up how SAII is assessed and justified. 

In this article, Thea Kane and Sian Griffiths explain what the new SAII guidance does differently and what can be learnt from a recent Land and Environment Court decision. With their significant experience delivering BDARs for our clients, Thea and Sian explain what the updates will mean in practice for developers and how to get prepared. 

What is SAII?

For many NSW development projects, biodiversity assessment is a well-established part of the approvals process. However, where a proposal has the potential to impact threatened species at risk of a Serious and Irreversible Impact (SAII), the level of scrutiny can be higher. 

A SAII occurs when an impact is considered likely to threaten the long-term viability of a threatened species or ecological community. These impacts are regarded as the most severe biodiversity outcomes under the NSW Biodiversity Assessment Method (BAM) framework and can have a major influence on approval pathways, project design and development outcomes. 

For project developers, this means that understanding whether SAII candidate species could be present on a site is becoming increasingly important at the earliest stages of project planning. Consent authorities now require sufficient information to assess any potential SAII risks before making their determination, rather than relying on further investigations after approval. 

What is different in the new guidance?

The update doesn’t change the SAII test itself, but it significantly tightens how SAII is assessed and justified. Key takeaways from the updated SAII guidance include: 

• Greater scrutiny of SAII: The guidance introduces a more structured and transparent assessment framework, which is likely to result in more consistent decision-making and a higher standard of justification.
• Higher evidentiary requirements : Assessments will need stronger scientific support, drawing on current literature, recovery plans and robust datasets. This may increase survey, analysis and reporting requirements. 
• Stronger focus on extinction risk: SAII assessments must clearly demonstrate how a project’s residual impacts could contribute to extinction risk, rather than simply describing the scale of impacts.
• More precautionary approach where uncertainty exists: Decision-makers may take a more conservative position where species presence, population data or impact pathways are uncertain, increasing the importance of robust baseline studies. 
• Consideration of cumulative impacts: Existing approvals, landscape-scale pressures and other threats may be considered when evaluating significance, potentially increasing SAII risk for projects in already stressed environments.
• Mitigation and offsets do not influence SAII determinations : SAII must be assessed based on residual impacts after avoidance and minimisation measures. Neither offsets nor proposed mitigation can be used to avoid a SAII finding by a decision-maker.
• Additional and appropriate measures only apply after a SAII determination: Where a SAII is identified, additional measures may be considered by the decision-maker, but they do not alter the SAII conclusion itself. 

Practical considerations for developers

One of the most important takeaways for developers is the value of identifying SAII risks as early as possible. 

The threshold for demonstrating or refuting SAII is now much more rigorous and there will also be less flexibility in borderline cases due to clearer thresholds. So longer lead time for detailed surveys will be critical for ensuring availability of information to inform avoid and minimise measures. 

Decision-makers cannot consider mitigation or offsets when determining a SAII outcome. This means that the assessment must focus solely on the significance of the impact itself, irrespective of any proposed mitigation or offset strategy. Proponents must therefore prioritise avoiding and minimising impacts during project planning, as the proposed mitigation and offsets will not influence the SAII determination. 

Overall, the update is about making SAII determinations more structured, transparent and evidence-based, but it also increases scrutiny and approval risk where SAII is plausible.

Potential implications of recent NSW LEC decision

A recent NSW Land and Environment Court decision (McMonigal Investments Pty Ltd v Central Coast Council [2025] NSWLEC 1414) may have significant implications for BDARs involving SAII candidate species.  As a result of the court decision, additional scrutiny may be required on SAII during survey planning and reporting, which needs to operate in tandem with the updates to the SAII guidelines. 

The Court found that, while the BAM allows species credits to be calculated based on assumed presence, this may not provide sufficient information for a consent authority to determine whether a proposal would result in a SAII. In this case, the critically endangered Variable Midge Orchid (Genoplesium insigne) was assumed present because targeted surveys had not been undertaken during the optimal survey period. The Court considered that without information on the species’ actual presence and abundance, it was not possible to adequately assess potential impacts on the species’ persistence. 

Importantly, the Court reinforced that such information gaps cannot necessarily be addressed through future surveys, mitigation measures or conditions of consent. The required information must be available when the consent authority makes its decision. 

For developers undertaking a BDAR, this means that ‘assumed presence’ may not be sufficient for SAII assessment purposes, even where it remains acceptable under the BAM for offset calculations. So early identification of SAII candidate species is important, with seasonally appropriate targeted surveys. 

Avoiding SAII showstoppers

Take these actions to be prepared for SAII and reduce the risk of significant delays – or even showstoppers – impacting your project:

• Identify SAII candidate species as early as possible – assumed presence may not be sufficient for SAII assessment purposes, even where it remains acceptable under the BAM for offset calculations. 
• Plan your surveys thoroughly – seasonally appropriate targeted surveys may be necessary to support impact assessments and approval pathways, and missing survey windows could result in significant project delays, particularly for species with highly constrained detectability periods. 
• Design out impacts where possible – prioritising avoiding and minimising impacts during project planning is crucial, as mitigation and offsets cannot be considered by a decision maker when determining a SAII outcome.

Early engagement with BAM accredited assessors will be critical to ensuring your project avoids SAII risks. Niche’s team of more than 20 accredited assessors – and wider 100-strong team of ecologists – are experts in guiding our clients through these important project steps. 

Find out more

• Our expertise
• Our projects
• Contact us

Follow us

• LinkedIn
• Facebook
• Instagram

Excellence in your environment