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Ōhiwa Harbour

Ōhiwa Harbour is the second largest estuary in the Bay of Plenty, categorized as a shallow intertidal dominated estuary. Land use in the catchment is dominated by pastoral farming and forestry. There is an oyster farm located on the western side of the estuary. Ōhiwa Harbour is an area of significant conservation value with significant ecological, biological, wildlife, scenic, landscape, historic and cultural values. Ōhiwa Harbour is of significant cultural importance to a number of iwi. There are significant shellfish beds located within the harbour and along Ohope Beach which are important cultural/recreational resources.

Sedimentation has impacted the shallow upper reaches of the estuary, and fine muds are reducing the estuary health in these areas. High flows and currents are maintaining sandy sediments in the open regions of the estuary, which still support large seagrass beds, although these have been in decline since 1945 while mangroves have been expanding. Recently the 11-armed seastar populations have greatly increased in the harbour and are having negative impacts on the green lipped mussel and pipi beds.


Estuary summary

What makes my estuary unique?

Explore the characteristics of this estuary


Estuary characteristics

  • Significant features
    • Harbour is an classified as "Outstanding " and a "Site of Special Wildlife Interest".
    • Is the site of numerous Pa and other archaeological sites of cultural significance.
    • Outstanding importance as a traditional Maori fishing area. 
    • Mangroves reach the south-eastern limit of their natural range in Ohiwa Harbour.
    • Uretara shellbank provides important bird roosting habitat.
    • The Ohiwa Spit provides a high tide roost for breeding New Zealand dotterel (Ohope Spit Wildlife Refuge).
    • Motuotu Island Nature Reserve (70 ha).
    • Pataua Island Scientific Reserve (22 ha).
    • Uretara Island Scenic Reserve (73 ha).
    • Tern Island Wildlife Management Reserve (12 ha).
    • Nukuhou Conservation Area (15 ha).
    • Ohiwa Harbour Sandspit Wildlife Refuge.
  • Total area
    2770 hectares
  • Total shoreline length
    92 km
  • Tide
    Spring: 1.7m, Neap: 1.1m
  • Flushing time
    2.9 days
  • Key rivers
    • Nukuhou 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.

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.

Tunanui (Ōhiwa)

What do the Broad Land Cover Classes mean?

Land cover information on LAWA is grouped into land cover classes at two levels of detail – broad and medium. For this overview we are showing the six broad-level classes for the catchment.

  • Forest

    Inclusive of; indigenous and exotic forest.

  • Scrub / shrubland

    Inclusive of; indigenous and exotic scrub / shrubland.

  • Grassland / other herbaceous vegetation

    Inclusive of; tussock and exotic grassland and other herbaceous vegetation.

  • Cropland

    Inclusive of; cropping / horticulture.

  • Urban / bare / lightly-vegetated surfaces

    Inclusive of; natural bare/lightly-vegetated and artificial bare surfaces, and urban area

  • Water bodies
Monitored sites 13

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