Drainage Easements Are Now the Default: What the 2025 Stormwater Controls Mean for Your Next DA in the Sutherland Shire

If you’re preparing a Development Application (DA) for a site that falls away from the street—particularly in the Sutherland Shire—you’ve probably already felt the shift: what used to be argued as a “reasonable alternative” is now being assessed as a necessity test. Under the Stormwater Management Environmental Specification 2025, Council’s position is clear:

• Gravity to a lawful downstream connection is the expectation, and
• private drainage easements are the primary pathway when a direct Council connection isn’t immediately available.
• Refer - 2025 Stormwater Management

In practice, SSC is now prepared to refuse DAs outright if the applicant cannot prove they have exhausted all feasible easement options and only then justified an alternative solution (like infiltration or level spreaders).

The “new standard” in plain English

1) You must prove you searched every feasible easement corridor

The 2025 spec doesn’t just assume a single “lot immediately downstream” option. It contemplates alternative routes, including side properties and multi-property alignments that ultimately connect to a legal discharge point. Appendix B expressly calls for reviewing adjoining layouts and identifying more than one path, including routes that travel sideways before heading downstream.

2) “Genuine effort” now means documentary proof (not assertions)

Council’s spec requires documentary evidence that you made a genuine attempt to secure easements before DA lodgement, including written evidence and records. The spec also signals that compensation and legal fees are an expected reality in easement negotiations (i.e., not a surprise, not optional).

Appendix B goes further—setting out an approach that includes:

• preparing plans for each affected property,
• contacting Council for owner details,
• and offering reasonable compensation, ideally backed by a registered valuation. This aligns with what practitioners are now seeing on the ground: “refusal letters” without credible offers and valuation support are increasingly being treated as insufficient.

3) Alternatives require an engineer to say it’s physically impossible (not just hard)

The spec recognises that there are exceptional cases where stormwater infrastructure within a potential easement is physically unable to be constructed—and in those cases, Council expects justification supported by a letter from a suitably qualified civil engineer.

This is a higher bar than “commercially inconvenient” or “construction would be expensive.” It’s about objective constraints (e.g., permanent structures, level conflicts, rock, lack of lawful downstream connection)—the kind of evidence that stands up when decisions are reviewed.

4) Infiltration trenches and level spreaders are last resort—and Council-only

Under the spec:

• Most locations are not suitable for infiltration, and infiltration can only be approved by Council (not private certifiers).
• Level spreaders are only considered where it is not possible to secure an easement, documentary evidence of genuine efforts has been undertaken and exhausted, and site conditions are not suitable for infiltration. Also, level spreaders are Council-assessed only, and generally limited (the spec explicitly limits them to Category 1 in specified circumstances).
• The spec is explicit: private certifiers cannot approve infiltration and/or level spreaders as alternative discharge methods. If your stormwater strategy relies on infiltration or a spreader without proving easement failure first, you’re now building a DA around a refusal risk.

Why council is tightening the screws (policy reality)

Councils aren’t just “getting tougher”—they’re responding to downstream impacts and future liability exposure. In a real-world discussion about a rejected DA, the new regime is described as requiring an engineer to formally conclude that an easement is physically impossible, with higher evidential expectations and a clear shift in how councils assess fallout when downstream owners refuse easements.

The direction is consistent: DAs are being assessed as if they might be litigated later, so the file needs to read like a quasi-forensic brief, not a planning narrative.