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Wairoa River

The Wairoa River in the northern Hawke’s Bay is the region's largest with an area of 3,563 square kilometres.   The land-use in the catchment is mostly farming, predominantly hill country sheep and beef farming. Forestry is the second largest land-use.

The river is popular for water skiing, sailing, swimming and fishing.   The river mouth regularly closes up due to sea currents, and river water can back up causing flooding of low lying areas near the township.  HBRC manually opens the mouth using a digger when conditions are ideal and safe enough to do the work. 

The river is formed by the confluence of the Hangaroa and the Ruakituri rivers which meet at Te Reinga Falls, and it flows 65 km to drain into the sea near Wairoa township. Mean annual flow is 65.545 cumecs (at Maramaru NIWA site). The upper boundaries of this large catchment lie in the indigenous forest of Te Urewera National Park. The main tributaries of the Wairoa in the west and north-west are the Waiau River, the Waikaretaheke River draining Lake Waikaremoana, the Mangaaruhe River, and the Ruakituri River. The main tributaries on the eastern side of the catchment are the Hangaroa and Mangapoike rivers.
The Wairoa catchment is dominated by fine, soft sedimentary geology – sandstone and siltstone. The exception is the Waiau River in the farthest north-western part of the region, which has its sources in hard sedimentary greywacke and argillite. Only some small tributaries in the area of the Wairoa River mouth have alluvial deposits of gravels, sand and mud. The high amount of rainfall and comparably low infiltration rate in this catchment result in relatively low base flows, and an increased incidence of floods.

The climate in the upper Wairoa catchment is characterised by extremely high rainfall and cool temperatures while the lower catchment has a warmer, drier climate.

The land-use in the catchment is mostly farming, predominantly hill country sheep and beef farming. Forestry is the second largest land-use. The township of Wairoa is on the lower reaches of the river. Discharges from the meat processing plant and municipal sewage treatment enter the river below the township and are subject to consents, with stricter conditions being imposed on the freezing works consent. The river flats in the lower reaches are used for cropping, horticulture and pasture.

A wide range of fish is present in the catchment, including native species valued for fishing and as traditional Māori kai (food). The critically threatened longfin eel and the koaro (which is rare in Hawke’s Bay) can be found in the Wairoa catchment; also the inanga, bluegill bully, yelloweye mullet, shortfin eel, torrentfish, lamprey, Cran’s bully, common bully, giant bully, redfin bully, mullet, chinook salmon, common smelt, and black flounder. There are large populations of both brown and rainbow trout. The Ruakituri River has large trout populations in the middle and upper region, the Hangaroa River has trout in the upper reaches, and the Waiau River has populations of both trout species throughout its length, with high numbers of large sized trout in the remote upper reaches.

Sites 5

Monitored sites in the Wairoa River catchment

...retrieving sites.

No sites found.

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Scientific Indicators
Scientific data for this catchment

This dashboard shows information on the data collected by the regional councils for water quality indicators, analysed as state and trend.

The state for the catchment is represented by the median concentration for the parameter across all sites within the catchment and then compares that value to the quartiles for all monitored sites in New Zealand.

Click on the parameters state icons to compare this catchment with others in the region.

  • State

    State shows how the median of samples from this site compares to other sites

  • Trend

    Trend shows how the quality of water is changing over time. Depending on the sampling history duration, five and ten year timescales are available:

Can I trust this data?

The Cawthron Institute has worked alongside regional councils to verify the processes and methods used for data collection, laboratory analysis of samples collected and the statistical analysis and interpretation of the results presented.

If all Cawthron ticks are green, then you can trust this data. However, if one or more ticks are orange, then conclusions should be treated with some caution.

For more details on each tick, see our 'Can I Trust This Data?' Factsheet.

Can I trust the data?
Data Collection

All samples were collected using approved field protocols and have been analysed in accredited laboratories. Therefore the data shown here has been collected and analysed following best practice.


All samples were collected using approved field protocols and have been analysed in accredited laboratories.

Trend - Adjustment for flow

This data is not flow adjusted. National guidelines suggest that flow-sensitive variables are flow 'adjusted' before trend analysis. Therefore, any trends shown here may be affected by variations in flow across sampling occasions.


E. coli



Black disc





Total Nitrogen


Total Oxidised Nitrogen


Ammoniacal Nitrogen



Dissolved Reactive Phosphorus


Total Phosphorus

Download Data

.ZIP file of indicator readings for all sites in New Zealand

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