Stormwater and Flood Protection

You are here > Home > Council A-Z > Stormwater and Flood Protection

Stormwater and Flood Protection

Get Connected | Preventing Pollution | Flood Protection | Approved Products List

Stormwater is rainwater that is captured by gutters or which runs off driveways and roads. The water travels down the stormwater pipe network and is discharged into our rivers and the ocean. This section is about stormwater management and how you can help prevent the polllution of our water ways.

A fast flowing river in New Plymouth District.

Every year, New Plymouth District experiences a number of high intensity rainfall events. This means the control of stormwater flow is essential to prevent flooding and erosion and protect people and their property. We manage this flow through a single coordinated system for each catchment area which utilises:

Natural characteristics such as ponds, watercourses, wetlands and vegetation.
Urban infrastructure such as roads, drains and culverts.
The underground pipe network.

As New Plymouth and surrounding urban areas have grown, development within the stream catchments has meant businesses and residential properties are exposed to flooding during extreme rainfall events. A number of flood protection structures have been put in place around the district, but there are also things residents and businesses can do to protect themselves and their properties from floods.

Flood protection

Climate change and stormwater

Climate change is expected to increase the annual rainfall in New Plymouth District. This may not result in more rainfall days per annum, but will more likely mean that the rainfall we do receive will be heavier. It is predicted that rainfall intensity for storm events lasting longer than four hours are expected to increase at an average rate of 0.21mm per annum for the next 50 years.

And did you know that a one per cent increase in the average air temperature results in an eight per cent increase in the atmospheric capacity to take up moisture - which means more rain. Mid-range projections for New Zealand are for an increase in the annual average temperature of 1.6 and 2.0ĒC from 1990 to the 2080s (source: www.mfe.govt.nz).

Keeping our waterways clean

When it rains the water literally washes the roads of vehicle pollution, animal faeces and litter. Because stormwater is not usually treated, these pollutants end up in our streams and on our beaches, causing irreparable environmental damage. At this stage the impact of this run-off, in public health terms, is within acceptable levels. If this changes, treatement of our stormwater or other options will need to be considered.

Residents and businesses play a big role in keeping our rivers, lakes and beaches clean.

What you can do to stop pollutionReturn to top

Floods, leaks and maintenance

Gushing water? Missing manhole lid? Blocked drains or culverts?

We are responsible for 1,432kms of water, sewage and stormwater pipes throughout the district. This includes the pipes right up to your boundary.

In general, if there is a water course or open stormwater drain on your property, it is your responsibility to keep this clear and clean of debris. We spend a considerable amount of time and money clearing vegetation and rubbish from our streams and culvert inlets. By letting garden waste and other refuse accumulate on stream banks and be washed downstream you may be unwittingly blocking our flood protection network and putting other people and property in jepordy.

If you notice gushing water, flooding on public property (parks, roads, footpaths) or someone putting something other than water down a stormwater drain (such as paint or oil) please let us know - giving as much information as possible (e.g. location, quantity, etc).

Contact us on 06-759 6060 (24 hours a day, seven days a week) or use the online contact us form below.

Did you know ...

There are 265km of stormwater mains running underneath the streets of New Plymouth District.
More than 565m of tunnels make up our stormwater network (305m in Bonithon Avenue, 110m in Queen Street and 150m in Gilbert Street).
There are 4390 stormwater manholes throughout the district.
Nearly all of the stormwater pipes are under 50 years old with most built 20-30 years ago.
The replacement value of our stormwater system is $81 million.
It only takes one litre of oil to contaminate a thousand tonnes of water.
It is estimated that 70 per cent of stormwater pollution is caused by cars (through metals such as lead, copper, zinc and oil washing off roadways).

Stormwater and Flood Protection