Project Title: Restoring Mill Stream, a tributary of the Mahurangi River



Metres Planted:
285 m

Volunteer Hours:

Location: 96 Hepburn Creek Road, Warkworth

GPS Coordinates: -36.416931, 174.673958

Project Cost: NZD $20236.7

Cost per Metre: NZD $71

Metres to be planted: 510m

Field Partner: Queen Elizabeth II National Trust

Project ID: NI21

Project Description:

Update JUly 2018

Thanks to the contribution from Scrub Growers Ltd and other cost cutting measures, we have a revised fundraising target of $20,000.  If we can make it to $20,000 we will have the funds needed to get all the plants in the ground, and maintain them to ensure they thrive.

We had a great community planting day. 40 superstars from across the Auckland region turned out to put over 1,000 plants and trees in the ground. What an effort! 

UPDATE June 2018

Scrub Growers Ltd ( is donating half of the plants needed for this project!

This generous contribution means that we can go ahead with prepping the site and planting this winter!

Save the date for a planting day! Lynne Butler and Trevor Lund are hosting a community planting day on Sunday 8 July to kick off planting up the site. More information coming soon.


Hi, we’re the Simperingham family.

The farm has been in our family since 1989. Our parents, Emily and Ted Simperingham bought the farm as a home and place for their retirement. They left Auckland to take on managing this special part of paradise.

They bought the property with a view to living off the land. They were attracted by the property’s “vibe” and in particular its height above sea level, its native trees and rolling pasture, and its position at the confluence of two streams.

Ted was able to divine water. He found a water source (a natural spring) which remains the principal source of water for the house and livestock today. The farm comprises about 60 acres. Originally it was leased to a local sheep farmer. In time, the property was switched to cattle. The cattle have been fine but the farming operation is of neutral financial benefit at best.

Ted has now passed away, and at 85 the farm is too much for Emily to manage. It is owned by the Avoca Trust. The Avoca Trust is a family trust whose principal purpose is to hold the farm on behalf of Emily and Ted’s children, children-in-law, and grandchildren. While most of the family now live in Gisborne, the farm remains an important anchor for the family and the trust wants to keep improving the property for future generations. For these reasons the Trustees were keen to accept assistance from Auckland Council, QEII National Trust, and from Million Metres, to fence off one of the water ways and plant native trees.


The farm is bounded by two tributary streams of the Hepburn Creek, with one known locally as Mill Stream. At the bottom apex of the farm the creek is tidal and we have mangroves, but the streams rise quickly up either side to their headwaters in remnant kauri forest and the Parry Kauri Park.

The streams host a number of rare and ‘at-risk’ species including long-fin eel (tuna), koura and freshwater mussels (kakahi). Native galaxiid fish such as banded kokopu are also present in the shaded pools along the stream.

Hepburn Creek flows into the Mahurangi River below the town of Warkworth, and from there into the Mahurangi Harbour and finally into the Hauraki Gulf. Before there were roads, steamboats travelled up the Mahurangi providing goods and transport to Warkworth residents. Today people swim and kayak in the river and run and walk along its banks.

The primary land use in the Mahurangi catchment is pastoral farming. About a fifth of the catchment remains in native forest and there is some production forestry as well. The key issue for the river and harbour is from the effects of adjacent land-use and a Mahurangi Action Plan has been developed which encourages fencing and replanting in an effort to reduce sediment and nutrient flows into the river.

As part of the Mahurangi Catchment, we have been aware of the importance of stream protection to stop siltation of the Mahurangi Harbour. Over the years the family has fenced off different parts of the streams and neighbouring bush to exclude stock, to try and protect these values. We are really excited that the water quality is good enough that freshwater mussels (kakahi) and freshwater crayfish (koura) still live in the streams – something we want to make sure is protected.

This project will see livestock excluded from the largest remaining portion of grazed pasture along Mill Stream. The area will be planted to provide additional riparian habitat and reduce sediment and nutrients from flowing in from the land.


As well as the streams, the bush remnants are really special parts of the farm. We border Parry Kauri Park and parts of our farm still have kauri ricker stands on them. We also have some beautiful large puriri and kahikatea.

There are a variety of native birds that live in area including visiting kaka. There is nothing more magic than looking down across the valley to see kereru swooping over the bush in summer.

On the opposite bank of the stream, our neighbours Trevor and Lynne have two Queen Elizabeth II National Trust covenants that are already mature native bush. Our plantings will add to the habitat created by these bush covenants.

Tree planting has always been a big part of the farm, which used to have a lemon orchard, and now has areas of black walnuts planted on it as a long term woodlot for future generations to harvest. At 60 acres the farm is not a very profitable enterprise, but the family are still keen to keep doing their bit to help improve the quality of the environment.


The stream banks are quite steep and were starting to erode in places increasing sediment flows into the stream. An old fence on the stream edge had become undercut by the stream, allowing cattle to access the stream in places with a risk of them finding their way into the neighbouring QEII covenants.

Last year, with the support of Auckland Council, we built a new fence at the top of the riparian slopes and as a result retired 0.8 hectares along the stream from livestock grazing. The fence now protects the stream and the stream banks from the impacts of cattle, and the land has already started to stabilise.

Now we want to plant the retired 510 metres of stream bank with 6,500 native trees and plants. QEII National Trust have helped us develop a planting plan and we will be using eco-sourced plants from a local nursery. We will plant predominantly coloniser species such as manuka, kanuka and coprosma, but we will also include some smaller numbers of trees such as kahikatea, puriri, titoki and kowhai that will eventually form the mature canopy. Where the stream first enters our property it widens to form a small open wetland, which we will be planting with a range of native wetland plants including cabbage trees, flax and native sedges. 

When costing the project we have allowed for some initial weed control at the site to remove kikuyu that would otherwise smother our new plantings. Plant supply, delivery and planting are the largest costs of the project, but we have also allowed for some materials such as stakes and fertiliser, as well as Million Metres 15% admin fee.

In conjunction with QEII National Trust, and our neighbouring covenant owners Trevor and Lynne, we will be hosting a community planting day sometime in May or June to start the planting off. It will be incredibly exciting to see the first plants go in the ground!

We will provide the post-care for the project, releasing the plants from weeds to ensure that they survive, until a closed canopy is formed in 3-5 years and the plantings will then become self-sustaining.


Planting up these waterways on our farm will help improve the health of the stream by increasing shading and reducing sediment from getting into the water.

Make a donation today and help us get the trees and plants in the ground this winter! You can donate ANY amount.

Planting up our section of the stream will extend the native bush from Parry Kauri Park and the protected native forest of our neighbours.

Thanks for your support!


Progress Photos: