Asset management

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What's involved •
Main assets

Waikato Regional Council manages over $1.1 billion worth of flood protection, river, lake, and drainage assets across the Waikato region.

These assets, including stopbanks, floodgates, pump stations, spillways and channels, form integrated networks of flood management and land drainage schemes.

They help safeguard lives and property, enable productive use of land, and protect services such as water supply, power, telecommunications and state highways and roading networks.

The majority of our schemes were built between the 1950s and 1970s.

As a result, many are now approaching the end of their operational life.

Over the next 50 years, we expect to invest over $1 billion on flood management and land drainage infrastructure.

In addition, a further $1.87 billion is expected to be spent on non-capital costs, including ongoing operating and maintenance, and depreciation.

Long term planning is essential to ensure this infrastructure remains effective and affordable for future generations, particularly in the context of climate change, land subsidence, changing land use, and evolving environmental legislation.

Decisions to maintain, renew, or replace assets are based on:

asset condition and age
risk and criticality
performance against agreed levels of service
whole‑of‑life cost and affordability
environmental and climate considerations.

We prioritise investment based on risk to people, property, the environment and economy, and deliver this work in partnership with local communities, landowners, iwi and district councils.

What's involved

Planning ahead

Long-term direction is guided by the council’s 50-year Infrastructure Strategy.
The Regional Asset Management Plan provides a clear, practical framework for planning, managing, maintaining and improving key infrastructure assets, supporting community safety, environmental outcomes and long‑term sustainability.
Funding, priorities and service levels are agreed with communities through the council’s long term plan.

Levels of service

Levels of service (LoS) describe scheme outputs we agree to deliver and drive our design and maintenance decisions. LoS include

the level of flood protection or drainage service communities receive*
acceptable risk thresholds
performance, reliability, and response expectations.

These LoS are

anchored in legislation
agreed with communities and catchment committees
reported publicly through performance measures and KPIs as part of the council’s annual report.

*Each scheme is designed to protect against certain-sized events and no more. Once built, design standards and levels of service can drift apart. For example, a scheme may be designed for a 1% annual exceedance probability event (often referred to as a 1-in-100 year event), but over time improved flood estimates (knowledge), climate change (higher rainfall and sea levels), catchment changes (land use changes, development, or higher or faster runoff), and cost pressures (operational, maintenance, regulatory, and meeting new environmental standards) can reduce the level of service from the original design.

Looking after assets

Regular inspections and condition checks.
Routine maintenance to prevent small issues becoming major failures.
Renewing or upgrading assets when they reach the end of their useful life or aren’t performing as designed to.
Responding quickly during and after floods and storms to ensure schemes are operational and to repair damage.
Regular service level reviews using updated hydrology, hydraulic models and surveys.

Main assets

Flood assets need to be managed and maintained. A small failure can lead to a lot of damage!

Stopbanks are engineered earth embankments, covered in grass, built along a waterway to prevent flooding of land, properties and infrastructure. Some communities have floodwalls, which are like a solid fence. Stopbanks and floodwalls are designed to protect against flooding from certain sized flood events, therefore, a flood event greater than design level may overtop and cause flooding.

Risks to stopbanks: Stock damage, toe erosion, old large trees, blackberry or gorse compromising structural integrity, crop growing on stopbanks, natural settlement, access issues, urban development, heavy vehicles, earthquake damage.

Risks to floodwalls: Natural settlement, sediment buildup, toe and joining area erosion, urban development, heavy vehicles, tampering, earthquake damage.

The Waikato region has more than 600 kilometres of embankments, including these foreshore stopbanks in the Hauraki Plains that hold back the sea.
Some stopbanks are designed to be overtopped and are called spillways. Spillways overtop into ponding areas to relieve pressure within a flood scheme.

Risks to spillways: Stock damage, toe erosion, old large trees, blackberry or gorse compromising structural integrity, crop growing on stopbanks, natural settlement, access issues, urban development, heavy vehicles, earthquake damage.

The Kauaeranga River spillway floods farmland and State Highway 25 during an extreme event, to protect Thames township from flooding impacts.
Stoplogs are steel or timber barriers stacked together across a designated gap within a flood protection system (stopbank, floodgate or pump station) to temporarily block the flow of water when required.
A floodgate is a movable barrier used to control the flow of water. There are many types. A gravity floodgate is a hinged or flap style gate that uses gravity and water pressure to move water from canals/drains into rivers and out to sea and automatically closes when the river is too high (for example, during flood or high tide). A control floodgate is deliberately operated to regulate water discharge to achieve specific water level outcomes.

Risks to floodgates: Obstruction by weeds and debris, earthquake damage.

The floodgates at Mill Road pump station move floodwaters by gravity from the land, through a stopbank, into the Waihou River. If the river level is too high, the gates close to prevent water backflowing to the land, and the water is pumped over the stopbank instead.
For some low-lying areas, floodgates alone cannot adequately drain the land. Pump stations pump water through or over stopbanks into the river. The pumps are automatic, starting and stopping when the water gets to a set height.

Risks to pump stations: Erosion around structures, weeds and debris, vandalism, electricity cuts, earthquake damage, pump failure, land subsidence

These two fish-friendly Archimede’s screw pumps in Hampton Downs are part of the Lower Waikato-Waipā Flood Control Scheme and each measure 18 metres in length, 3 metres in diameter and can pump a maximum flow of 2.25 cubic metres per second.
These are storage areas for flood waters. Usually they are natural depressions, lakes, wetlands and/or river channels and wide flood plains. A spillway will divert flooding into these designated areas to relieve pressure on a flood scheme.

Risks to ponding areas: Development in ponding areas may reduce storage ability.

Lake Waikare and Whangamarino Wetland are used for large-scale flood storage, accepting water diverted from the Waikato River via a spillway at Rangiriri to reduce peak floods for Meremere, Rangiriri and Mercer.
These are manmade channels used to move water from the land to floodgates and pump stations. A canal is a bigger drain. Our drainage networks are designed to remove ponding in time to prevent pastural damage (within three days) from a 10-year rainfall event, rather than prevent flooding altogether. In the Waihou River and Piako River catchments there are also drainage schemes managed by district councils.

Risks to drains and canals: Weeds and debris blockage, bank erosion and silt buildup, earthquake damage and crops growing adjacent to drains.

Our largest drainage networks and canals are on the Hauraki Plains and part of the Piako River flood protection scheme.
Land was acquired for the various flood protection schemes and land acquisition continues today as required for scheme maintenance, upgrades and renewals. Some of this land is leased to adjoining landowners under controlled arrangements that protect the primary flood protection function of that land.