River running through hills

Detention Bunds

Research & Monitoring – With Descriptor

About the project

An ecosystem services report commissioned by Living Water identified widespread use of detention bunds as a potential solution for slowing water flows, removing sediment and improving overall catchment resilience. Engineers were engaged to design and build detention (earth) bunds in flow paths to collect and slow the release of stormwater on two farms. The ability of these structures to reduce peak flow and capture sediment in the Northland farming landscape is currently being assessed.

Following assessment results, we will evaluate the cost-effectiveness and water quality outcomes of using detention bunds throughout the entire catchment. In turn, this will determine whether they can effectively manage peak runoff in Northland.


  • Reduced sediment to waterways


  • Construction completed April 2018
  • Monitoring completed December 2020
  • Ongoing maintenance 

News updates

  • See vlog explaining bunds here and timelapse here
  • Have held up well in heavy rain events in Northland in June 2018 

Detention bunds are essentially speed calming devices. They slow water flows down giving the environment a lot more time to treat the water on its way through.

Matt Highway
Catchment project image

Detention Bund Trial video

Watch Fonterra Sustainable Dairying manager, Matt Highway talk us through the purpose of detention bunds, when and where they might be useful and what we're hoping to learn from this trial.

Concept and detailed design

Completed early 2017

Progress: 100%

Project Implementation and Construction

Completed April 2018

Progress: 100%


Started early 2018 - will finish end 2019

Progress: 80%

What’s Next

  • Complete monitoring to determine how effective detention bunds are at slowing water flow and trapping sediment
  • Test scalability of implementing detention bunds catchment-wide and beyond
  • Establish the best ways of supporting partners to build detention bunds as a widespread freshwater improvement tool

Read our case study