Avon-Heathcote Estuary/Ihutai

The Avon Heathcote Estuary/Ihutai is a large shallow estuary located on the eastern fringes of Christchurch City. It is separated from the Pacific Ocean by a 4.5 long sand spit that forms the triangular shape of the estuary. The estuary contains fresh water from both the Avon River/Ōtakaro and Heathcote River/Ōpāwaho, and salt water from the ocean.

The main pressures on the estuary are sediment, nutrients, and contaminant run-off from rural and urban land uses, storm water, and sewage discharges from broken or leaky pipes, or overflows from heavy rain. Passive discharges from historic landfills, and faecal matter from birds are also contributing to pressures on the estuary.

The benthic communities within Avon-Heathcote Estuary/Ihutai range from 'fair' to 'poor' health.

The estuary has diverse features including mudflats, sand banks, salt marsh, seagrass beds, shrubland and coastal bush.

The area is home to 144 bird and 34 fish species, and is taonga for mana whenua, having been a place of settlement and source of mahinga kai. It also has high recreational values for the wider community.

Estuary summary

What makes my estuary unique?

Explore the characteristics of this estuary

Overview

Estuary characteristics

Significant features
- Largest semi-enclosed shallow estuary in Canterbury.
- Home to 144 bird species, including at-risk native wading birds, and 34 fish species.
- An internationally important site for migratory birds, including the bar-tailed godwit/kuaka.
- Nursery and spawning ground for several fish species, including sand flounder/pātiki.

Total area
830 hectares

Total shoreline length
5.3 km

Flushing time
5.6 days

Key rivers
- Avon River/Ōtakaro
- Heathcote River/Ōpāwaho

Highlighted reports

These links are from your regional councils and unitary authorities and provide additional information about this estuary

The sediments and biota in the Avon-Heathcote Estuary/Ihutai 2007-2013 The sediments and biota within Te Ihutai/Avon-Heathcote Estuary 2007-2021

Related factsheets

For more details on particular topics see these factsheets

Understanding estuaries Estuary types

Department of Conservation

Want to connect with restoration groups or explore your local estuary? You can find more information on the DOC’s interactive maps.

Restoring estuaries map Experiencing estuaries map

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.

Avon/Ōtākaro and Heathcote/Ōpāwaho River Estuary Catchment

37 sites

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.

Avon/Ōtākaro and Heathcote/Ōpāwaho River Estuary Catchment

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