Waikanae Estuary Scientific Reserve

Visiting the reserve

There are a number of easy short walks in the Waikanae Estuary Scientific Reserve, mainly on the southern (Paraparaumu) side. The walks are suitable for buggies. 

Getting there

The reserve is located mainly on the southern (Paraparaumu) side of the estuary. There are access points off Manly Street and at the corner of Otaihanga Road and Makora Road. The northern (Waikanae) side of the estuary can be accessed from Tutere St – it is mainly administered by the Kapiti Coast District Council. 

Know before you go

Beware of soft sand near water. The changing course of the river affects the water table beneath the sand and can cause quicksand conditions.

Because of the reserve’s special ecological values, there are a number of restrictions to limit human impacts, which are displayed on signs. The most significant are:

• no vehicles or cycling in the reserve
• no horses apart from on the dunes track from the Tutere St carpark to the beach
• no dogs, apart from dogs on leads on:
  • the main Reserve Link Track between Otaihanga and Manley Street
  • the dunes track from the Tutere St carpark to the beach.

Species in the reserve

The river and estuary are a tidal home and airport to a variety of waders and sea birds. More than 60 species of birds are found there, including banded dotterel, pukeko, dabchick, and variable oystercatcher. They occupy the sandspit where the river affords some protection from the increasing numbers of cats, ferrets, dogs and vehicles on the other side of the reserve. Flocks of white-fronted terns, shags, gulls and penguins roost on land but rely on the sea for small fish and shrimps.

Domestic travellers – such as wrybills and black-fronted terns from Canterbury – stop over, as do the international migratory birds, such as godwits and knots from Siberia.

Royal spoonbills have nested on Kapiti Island since the early 1990s, and they regularly visit to feed in the shallow waters of the estuary. The birds depend upon the constant movement of the river and the tide which opens up twice a day to reveal a feast of worms, shellfish and crabs. If the river and sand is stabilised too much these intertidal flats will dry out, forcing the birds to leave.

As a part of their life cycle, many native fish species require both freshwater and saltwater. For example, the whitebait species mature in the freshwater, spawn in the inter-tidal zone and their young go out to sea to return as whitebait. Eels mature in the river, go out to sea to spawn and return as transparent glass eels.

Five species of galaxiid fish make up the whitebait catch. The īnanga, kōaro and banded kōkopu are the most common but the giant and short-jawed kōkopu are rare. 

Modification of the catchment area, such as the removal of stream vegetation, urban development, increased sediment and pollutant levels, and obstructions to fish passage such as culverts have impacted on the fisheries values. Fish need unimpeded access from the marine environment to the upper catchment areas. Some species use the river as a highway, sometimes climbing huge waterfalls to reach their preferred habitat.

Living carpets

Carpets of remuremu, Selliera radicans, grow in the firm mud along the waters of the estuary. They vary according to the flow of the river and the development of the wetland. The mosaic of tidal sandflats, sand dunes, salt marshes and lakelets provide a home for this and more vulnerable plants such as two regionally rare carex species. Many of these plants have disappeared because they are very sensitive to changes in water quality and introduction of weeds.

River's end

From the Tararua Range, the Waikanae River once flowed through dense forest which reached almost to the sea. At a point near the present railway bridge, the river split into two channels flowing through swamp forest and salt marsh, meeting again at the dunes and lakelets of the estuary. Here they cut through sandhills, some 10 metres high. The river now flows through a single channel to the sea.

Middens, observation posts, pa and burial grounds are reminders of early Māori who moved through the area. Ngāti Apa, Rangitāne and Muaūpoko were followed by Ngāti Toa, Te Ātiawa and Ngāti Raukawa. The estuary is the site of the 1839 Battle of Kuititanga where Te Atiawa, who had established pa on both sides of the estuary, fought Ngāti Raukawa, forcing them to flee to Ōtaki. The area is sacred to the people of Ātiawa ki Whakarongotai who are tangata whenua of this area.

In 1886 the Manawatū Railway opened the coast to more European settlement. Flaxmilling and farming settlements ripped away much of the coastal forest, exposing the river’s flanks to erosion. Since then, housing, flood protection, gravel extraction, stormwater, farm waste and industrial discharges have further diminished the power of the river.

Creation of the reserve

Since the 1960s, the land around the estuary has been transformed from a coastal wilderness to a densely populated urban area. In the 1970s, the Waimeha Swamp was drained and blocked to create the Waimanu Lagoon and traditional whitebait spawning grounds were lost. Hundreds of residential sections were developed to the north of the river.

Conservationists helped to establish Waikanae Estuary Scientific Reserve in 1987 to protect the remaining area. In the 1990s, though, subdivision crept closer to the estuary, increasing the threats to wildlife from pets and disturbance by vehicles.

DOC is embarking on an ecological restoration project for the estuary, complemented by the restoration work being undertaken by Waikanae Estuary Care Group, within the scientific reserve and on the adjacent Kapiti Coast District Council administered land.