Karoro Stream rehabilitation
Whanganui District Council has partnered with GasNet to tidy up the watercourse at the end of Karoro Road in Gonville. This watercourse was probably one of the original estuary outlets for this catchment, but has been affected by intensified industrial and urban development in the surrounding area over many years.
As part of the project, gas mains were renewed and lowered so they do not cause an obstruction for flows during rain events.
More appropriate riparian type planting was also done along the length of this watercourse.
Awarua Stream makeover – Wikitoria Road culvert
The Council worked with Horizons Regional Council on an enhancement initiative for a section downstream of the Wikitoria Road culvert, which will included some removal of alien plant species and revegetation with appropriate riparian-type planting.
Matipo Street watercourse rehabilitation
In 2017, the Council partnered with the Matipo Community Development Charitable Trust to revitalise the section of the watercourse at the end of Matipo Street. Local residents did the planting work as part of a training initiative through Land Based Training towards a qualification in horticulture.
Kaikokopu Stream revitalisation project
In early 2016, the Kaikokopu Stream was identified under the Healthy Streams Initiative as an area which required remediation in order to provide ecological, environmental and hydrological gains.
A project was initiated to revitalise a 700m section of the stream that traversed Council land.
Environmental solutions were implemented to provide ‘soft engineering’ solutions to manage any adverse effects. These environmental approaches included the decrease in the angle of bank slopes, scour protection through the use of eco-matting and grass resurfacing, planting a range of New Zealand native riparian plants, the construction of rock pools at strategic positions and the construction of a fish passage, to allow access through a culvert pipe.
Since this project, the stream has performed better hydrologically, and future fish surveys will determine the effects on ecological conditions of the stream. We continue to monitor the stream’s condition and will consider further enhancements for inclusion in the Long Term Plan.
London Street watercourse rehabilitation
The London Street Watercourse Rehabilitation was initiated in late 2016 on 250m length between Glasgow Street and Victoria Avenue (beside the railway). Prior to the remediation works, the watercourse was clogged with invasive vegetation that slowed water flow and was an eyesore for those walking in the area.
This watercourse was targeted in order to provide a better hydrological, aesthetic and environmentally conscious situation. Environmental solutions were implemented to soften the look of retaining structures that were constructed on vulnerable slopes. To prevent erosion, eco-matting and grass was established on the steep slopes, and New Zealand native plants were planted among mulched product on the shallow slopes. During the course of the project, it was noted that a number of eels were living in the stream. This was quite surprising as the watercourse is only connected to the river through a network of stormwater pipes, with the most direct piped route exceeding 1.5km long.
Kaikokopu Stream: vertical brush walls
A section of the Kaikokopu Stream (between Somme Parade and Boyd Avenue) has had some sections of its banks strengthened, thanks to the Healthy Streams Whanganui project and funding from the Whanganui River Enhancement Trust (WRET).
The Kaikokopu Stream was eroding a section of Council land in Boyd Avenue, which may have caused an erosion risk to Somme Parade. To strengthen the embankments, two vertical brush walls have been created using a sterile dwarf willow species.
The roots of the dwarf willows will stabilise the embankment and the species will remain in place and not self-seed. The willows also release excess moisture from the embankment into the atmosphere and this reduces the weight of the earthen wall surrounding the bank. The vertical walls will allow the banks to maintain a steep angle – in this case the brush wall is 5.5m high.
Awarua Stream fish passage creation
Awarua Stream, in Pūtiki, is one of the streams in which is getting a makeover in the Healthy Streams project.
Part of the Awarua Stream makeover was completed in May 2014. Two fish passages were constructed, one at the crossing of Wikitoria Road and the other at the intersection of Nepia Road and State Highway 3. This work, thanks to funding from the Whanganui River Enhancement Trust, will make it easier for native freshwater fish to make their journey from the Awarua Stream to the Whanganui River.
Fish passages are created by adding rocks to the water flow to allow fish to navigate the stream and by lowering perched culverts (pipes) so fish can travel through the whole length of the stream.
The native plantings made by children from Te Kura Kaupapa Māori o Te Atihaunui-a-Pāpārangi, Whanganui District Council and Horizons Regional Council in November 2013. The trees are maturing and more plants have been added, thanks to Sustainable Coastlines.
Awarua Stream makeover
In November 2013, children from Te Kura Kaupapa Māori o Te Atihaunui-a-Pāpārangi joined staff from Whanganui District Council and Horizons Regional Council to plant native species around Awarua Stream in Nepia Road, Pūtiki.
The planting day was the first in a series of activities under the Healthy Streams Whanganui initiative.
The children planted appropriate species around the edges of streams to provides shade and create stable embankments, which helps maintain a natural flow pattern for the stream to make it easy for fish to swim to breeding areas. By following best practices for planting, the quality of the water is also improved as plants remove pollutants from streams, reduce silt and help to prevent erosion of natural water courses.