Erosion control | Hamilton City Council

Project summary

What we're doing

Our city is made up of gully systems and streams that flow into the Waikato River. Stormwater runoff flows into these streams and can cause erosion, sedimentation, and other water quality impacts.

In the 2018-28 Long Term Plan Council approved $37.5 million for erosion control projects in the city's catchment and gully systems:

Te Awa O Katapaki
Kirikiriroa
Mangaheka
Mangakootukutuku
Waitawhiriwhiri
Mangaonua
Otama-ngenge

Gully remediation work involves maintenance, weeding, controlling pest plants and planting native species, strengthening banks, plus positioning rocks and logs to naturally mitigate erosion. Council works together with residents and community groups to improve our natural habitats for future generations to enjoy.

Why we're doing it

We'll never stop erosion, but we can help mitigate it so there is less sediment and higher water quality, creating a vibrant environment for plants, birds, eels, fish, and people to flourish.

This project will

Increase native plant coverage across Hamilton
Protect and improve our Significant Natural Areas
Improve water quality in the Waikato River

Project features

$37.5M
A major investment in improving habitats and protecting our waterways from erosion, citywide.
Seven gullies and catchments
We're working with contractors and community groups to improve seven natural areas across Hamilton.
A cleaner river
Works will reduce sedimentation and improve water quality in the Waikato River.

Where we're at with progress

Stage 1 - Planning

2018
$37.5M dedicated to erosion control projects in the 2018-28 Long Term Plan.
Stage 2 - Underway

2020
Work began on erosion control projects in catchments and gullies around Hamilton.
Stage 3 - Completed

2028
The project is due to be completed by 2028.

Frequently asked questions

How will this upgrade be funded?

These upgrade works were funded in the 2018-28 Long Term Plan.

What causes erosion?

Erosion rates in New Zealand are naturally very high by world standards, caused by steep slopes, erodible rocks, generally high rainfall and common, high-intensity storms. For these reasons, Hamilton’s gullies are very susceptible to erosion. The impacts of erosion in our gullies include sediment and other materials entering our streams and waterways, affecting water quality and aquatic life.

How will these works reduce sedimentation in the river?

Some of our construction works will involve water control (such as pipes and drop structures), weeding and replanting native trees, constructing dams for debris, ground recontouring, reinforcing stream banks, and water diversions (where we reduce the speed the water flows). We will also be building paths and boardwalks for public access, ensuring our community can access and enjoy the gully without damaging the natural environment.

What happens when there is too much sediment in our river?

When there is a sedimentation problem in our waterways, it causes other ecological issues such as loss of aquatic habitat for eels, frogs, fish, and other wildlife. Water will look muddy, and downstream there will be water quality issues that impact other streams and rivers.