Let's not conflate the Three Waters debate with ‘fixing’ Auckland's flooding

As Auckland’s flood waters recede, what has been left behind amongst the mountains of damaged property is a cohort of equally tragic political finger pointers, intent on manipulating a rattled ratepayer base.

Auckland’s flooding, it has been claimed, is apparently all the evidence we need to implement Three Waters reform and an associated non-technical co-governance structure. I’m not convinced. If anything, it highlights just how complex this issue is. It’s a highly technical task to safely guide ever-increasing rainfall away from our homes, businesses and major public assets. But it appears that the public commentary regarding stormwater as it relates to Three Waters is almost completely devoid of expert engineering input, with some notable exceptions.

First, let’s put the January 27th 2023 rainfall into perspective. Exacerbated by (or the result of) a statistically unlikely third consecutive La Niña, and further fueled by a warming climate, early analysis indicates it was a 1% AEP event, more commonly known as a ‘1 in 100 year’. Calculating this is more complicated than it looks, but given rainfall volume was nearly double the size of the next largest event (1985) in the last 63 years of records, we can confidently say it was highly anomalous. A total of 245mm of rain fell (unevenly) on Auckland within 24 hours, and more startlingly, 16% of that total fell in just 22 minutes.

In practical terms, most of Auckland’s stormwater infrastructure operates to a 10% AEP event (there are many exceptions), broadly meaning the City received vastly more rain than what the majority of our system infrastructure is designed for. Add the crazy level of intensity, and there’s simply no practical way to deal with that much water all at once - widespread flooding was inevitable. Of course, Auckland could implement an entirely new city-wide design standard, but that would cost many billions.

Thank you, NIWA & Newsroom, for this great chart:

At its core, this is the financial problem that the Three Waters reform is attempting to solve: the necessity for asymmetric capital investment necessary to plan, design, build, own and then operate potable, waste and stormwater infrastructure. Given the ratepayer base, Auckland is pretty well placed to deal with this challenge relative to smaller regions. Thames Coromandel district, for example, doesn’t have the ratepayer revenue nor the balance sheet to fund the infrastructure required to deal with its hilly terrain, geographically disparate and seasonally active coastal settlements. If the various regions were to pool resources as proposed, it would be easier for the likes of the Thames Coromandel to fund capital works and maintenance. So, centralised funding is indeed one way of dealing with this regional disparity.

However, there are important nuances.

Potable (drinking) and waste water is largely easier to deploy and manage than stormwater. Potable and wastewater is fully reticulated, more predictable and all underground. Importantly, it’s also monetisable via consumption charges. Stormwater, however, involves a complex mix of above and below ground structures, hard and soft engineering, and interaction with other public assets such as roads, parks, wetlands and the coastal foreshore. Effective stormwater management requires an enormous amount of joined-up planning, modelling, GIS data, geotechnical surveys, asset maintenance, catchment management and most critically, town planning and associated development consenting. Relative to potable and waste, stormwater is also difficult to charge for on an ongoing basis.

So, putting aside a lack of pre-and-post event emergency management leadership (also Metservice seems a lot more active ex post facto?), there’s not a lot that could have been done in the short term to save Auckland from this deluge and its consequent disastrous outcomes. Similarly, anyone claiming that the Three Waters construct will somehow mitigate similar outcomes in a similar rainfall event, inside a 50-year timeframe, is either over-indexing on political ideology, or more likely, has no idea what they are talking about. The infrastructure does not and will not exist - not because the system for deploying it is broken, but because it simply costs too much relative to the rarity of the event.

In addition to those smaller regions needing a funding solution, another contributing factor leading to calls for change is that Auckland council has a communications problem (surprise!). Despite what you might have been led to believe, there is actually a vast and fairly sophisticated machine that manages the city’s stormwater infrastructure; it extends through a physical, technical, personnel and contractual network, operated by some of the best consulting engineers, modelers, council asset managers, planners, consenting specialists and financial analysts. Council does very little to explain the extent and complexity of this work to the public, nor it’s costs, challenges and successes. No wonder ratepayers don’t feel like they know where their money goes! Council just needs to say what they mean, not wrap it in marketing spin - it’s expensive, complex and necessary infrastructure work.

The lack of clarity feeds into a level of public mistrust; one of the ways this expresses itself is via the resource consenting process. Public pushback on stormwater infrastructure deployment causes time and cost delays for the region, even more so when it involves more visible soft-engineered structures such as wetlands, swales and planted zones. These may be the tools of the future when it comes to managing increased climate events, but they still require the same hydrological flow calculations, tolerances and detailed engineering design - only with additional land requirements and planning permission hurdles. Current legislation (and I suspect future, also) is geared to over-democratise what are basically foregone engineering conclusions.

This event has brought into focus for me that Three Waters may well result in worse stormwater management outcomes for Auckland, why? Because, (a) absent a remarkably unlikely weather event, the network infrastructure and deployment model is broadly working OK for Auckland right now, (b) centralisation of ratepayer assets and associated data will inhibit the necessary flow of information within what is already a complex system, and lead to additional friction in the asset delivery process, and (c) relatively rapid urban planning and land development consenting, and associated public consultation, will become out of sync with longer term regional infrastructure capex cycles.

So here are a few ideas on how to improve Auckland’s existing stormwater management system, as an alternative to Three Waters:

• Remove roadblocks: remove any consenting and consultation hurdles and create radical fast track permissions for critical stormwater infrastructure projects.
• Finance differently: investigate and implement new funding mechanisms such as central government backed green bonds, local levies and PPP structures for stormwater assets.
• Retreat gracefully: historic decisions to develop some parts of Auckland were made without the full understanding of climate change that we have now. It’s now time to look at what coastal and marginal land retrenchment is possible; it has been done before in Auckland to great effect and can deliver significant public assets in the process.

Aucklanders - stay safe navigating the roads, and the news cycle, over the coming days.

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Duncan Stewart is a director at Greenhouse Capital. He is a former project and programme manager at BECA for the Auckland Council Stormwater Capital Works Programme, co-founder of environmental consultancy Andrew.Stewart which assisted the Auckland Council stormwater consenting programme for 10 years, and co-founder of environmental compliance software company, CS-VUE.