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Waikanae Estuary

Waikanae Estuary is a moderate-sized, shallow estuary which drains onto a broad, flat beach just north of Paraparaumu. It is two kilometres long, approximately 50 meters wide, and 1-2 metres deep. The majority of Waikanae Estuary is a long, shallow lagoon which runs along the back of Paraparaumu Beach parallel to the sea.

Greater Wellington has carried out annual environmental monitoring in this estuary since 2010. An additional in-depth analysis of the animals living in the sediment began in 2017 and is carried out approximately every five years.

 

 

 

Ocean currents from the north generate a sandspit that pushes the mouth progressively southwards; however, the lower part of the estuary is periodically lost when the channel naturally realigns, or opens more directly to the sea at the north end before progressively again migrating south.

Floodgates restrict tidal action and flushing and diminish ecological values in the lower estuary by limiting the potential for long-term estuarine communities to establish. Higher up the estuary, conditions are much more stable, supporting saltmarsh and tidal flats with small freshwater lakes around the margins.

The Waikanae is usually freshwater dominated at low tide and at high tide consists of a freshwater layer on top of a saltwater layer. Plant and animal life is restricted to those that tolerate salinity extremes.

It is also one of very few sizable estuary and wetland areas in the southwestern North Island, and is a nationally significant wetland habitat for waders, seabirds and waterfowl, both local and migratory. More birds visit Waikanae Estuary Scientific Reserve than any other area in the Wellington Region.

The estuary is a local focal point for conservation, walking, picnicking, boating, fishing, paddling, bird watching, bathing, and whitebaiting. The system receives moderate inputs of nutrients and sediment from the catchment and treated wastewater enters the estuary from the Paraparaumu Treatment Plant via the Mazengarb Drain.

Estuary summary

What makes my estuary unique?

Explore the characteristics of this estuary

Overview

Estuary characteristics

  • Significant features

    This is an area of Significant Conservation Value.

    The estuarine site is an important nesting site for banded dotterel, dabchick, pūkeko, and also a breeding site for variable oystercatchers.

    Two threatened species are known in the ecosystem: sea sedge and swamp buttercup.

  • Total area
    80 hectares
  • Key rivers
    • Waikanae River

What's happening upstream?

See results from monitored river quality sites influencing this estuary

River quality

What's happening upstream?

The physical characteristics and health of estuaries are influenced by the rivers and streams flowing into them. For instance, when it rains the mud and contaminants generated on land can be washed into rivers and eventually flow into the estuary. The health of our rivers and streams can therefore be very important for Estuary Health, and understanding the upstream pressures can help with interpreting estuary monitoring data. Monitoring is undertaken for a range of river health indicators (e.g., water quality and ecology) in many catchments across the region. Where there are monitored river catchments that influence this estuary, these are shown below. You can click through to view monitoring results from these River Quality sites to see current state and how health has changed over time.

What surrounds my estuary?

See land cover information from monitored catchments that surround this estuary

Land cover

What surrounds my estuary?

The physical characteristics and health of estuaries are influenced by local geography and the way we use our land. This is because estuaries are the receiving environments for many of our land use activities. Land cover information can be used as an indicator of land use, therefore knowing the surrounding land cover can help us understand which pressures might be affecting Estuary Health. For example, the sandflats of estuaries surrounded by rural areas will typically contain contaminants related to rural activities (e.g., cadmium from crop fertilisers and copper from fungicides), whereas those surrounded by urban areas are more likely to contain contaminants associated with cities (e.g., zinc and lead from roads and building materials). Where there is land cover information available for nearby catchments, these are listed below. These figures show the types of vegetation and built or natural features that surround the estuary margins and the rivers that flow into this estuary. You can click through to the Land Cover topic to see these land cover classes broken down into further detail, and view changes over time.

Monitored sites 1

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