Gravel management in our rivers
Gravel from Northland's rivers has historically been put to a variety of uses right around our region, from roading to landscaping.
Taking river gravel is less common than it used to be – but can still offer significant environmental, economic and other benefits in some areas.
Formation of 'gravel islands' and other sediment build-up can divert the flow of water into river and streambanks, eroding them and allowing sediment to escape downstream. From there, it travels into our harbours, where it can become a serious pollutant, smothering shellfish and other marine life.
Gravel build-up also reduces the amount of water a river can carry in a flood, worsening the risk to humans and stock and causing damage/disruption to private and public property, roading and rail networks.
A build-up of gravel and other sediment worsening erosion along the Waihou River.
Locals in some flood-affected parts of Northland suggest the build-up of gravel in our rivers has worsened in recent times, attributing this to a reduction in the amount of gravel being taken – or in some cases – none being taken at all.
Interestingly, gravel build-up has far more influence on the outcome of the more regular, smaller floods common to Northland, than it does in less-frequent, but much larger storms. (This is because larger events like ex-Tropical Cyclone Wilma involve such huge volumes of water that rivers would spill their banks anyway – irrespective of any gravel build-up.)
A gravel bar and island are both restricting flow and worsening erosion at this spot on the Waitangi River.
Done correctly, gravel extraction can:
- Reduce riverbank erosion;
- Reduce flooding and sedimentation;
- Lessen the risks to people, stock and property; and
- Help keep important roading and other transport networks open.
Many people incorrectly believe gravel management is illegal in Northland.
In fact, Northland has many rivers where managing the build up of gravel may be beneficial in some circumstances and our rules either permit this (subject to certain criteria) or allow resource consent to be sought.
Gravel is also removed under river management schemes – including Kaihū and Kaeo – and in these cases, is typically funded by targeted river management rates.
However, in assessing possible benefits of any gravel management, careful thought needs to be given to a number of factors, including cost, what's potentially at risk and cultural and environmental factors.
Each case is unique and before work starts, you need to check it will meet the 'permitted activity' rules and standards spelt out in the Regional Water and Soil Plan for Northland – for more information go to www.nrc.govt.nz/rwsp
Where these standards can't be met – or in some other circumstances – you cannot take gravel without getting a resource consent first. The latter includes river/drainage schemes, some rivers with outstanding values and any activity that can't meet permitted activity criteria for maintaining the free flow of water in a river or stream.
Other Water and Soil Plan (RWSP) rules limit gravel extraction for private use to 100 cubic metres in any 12 month period. (Taking more than this also requires resource consent, although this limit doesn't apply when the gravel is being taken to maintain the free flow of water.)
Map of locations for potential extraction
Find a larger version of this map in pdf format (PDF, 400KB)
This location map shows areas in Northland where gravel resources exist in rivers that may be suitable for extraction.
Further details on gravel management and rules relating to extraction can be downloaded in our gravel management brochure (PDF, 290KB).
If you are interested in extracting gravel from a river, or have concern with gravel accumulation, please contact the Northland Regional Council River Management staff for advice on gravel management and compliance with associated rules before commencing extraction.
This gravel management information is also available as a brochure and can be downloaded in pdf format below.
Northland Regional Council River Management staff can be contacted for advice on gravel management and compliance with the RWSP.
Phone 0800 002 004
Information is also available on our website: www.nrc.govt.nz/rwsp
To manage risk associated with gravel management, our staff also keep a database of gravel management enquiries and activities.