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Waikouaiti River

The Waikouaiti River has the third largest catchment in Otago (425 km2). The north branch covers 283 km2 and the south branch covers 86 km2, they converge approximately 8 km upstream of it’s confluence with the Pacific Ocean at Karitane. The lower five kilometers of the river are saline.  

The catchment has indistinct boundaries for the most part, with no dividing ranges between it and neighbouring catchments. To the west it is bordered by the Nenthorn stream catchment, Three O’clock stream catchment and various other small catchments that drain to the lower Taieri River. To the north and east it shares headwaters with the Shag and Pleasant Rivers and to the south it is bordered by the Silverpeaks.

The average annual rainfall in the upper catchment is 740mm rainfall, in the lower catchment (Palmerston) it is 545mm.

Vegetation in the catchment has been considerably modified over the last 150 years. Extensive forest and tussock areas have been replaced by a mixture of high- and low-producing grasslands with scattered areas of remnant broadleaf and native and exotic forest. In the uplands beyond the confluence the pasture is mostly low producing with both native manuka/kanuka and introduced scrub in gullies. In the Silverpeaks, in the headwaters of the south branch, some native manuka/kanuka and broadleaved indigenous hardwood forest/scrub remains.

High producing pastures predominate in the hills and downs, river flat areas in the lower catchment below the confluence. The Waikouaiti estuary supports the largest remnant saltmarsh system in Otago, and is listed in the Water Plan as containing a scarce wetland type containing glasswort and jointed rush.

The Waikouaiti River is used extensively for whitebaiting between August and November, with inanga, koaro and banded kokopu all contributing to the whitebait catch.  The Waikouaiti River supports one of the most diverse freshwater fish communities in Otago, with 11 native and one introduced fish species present. Black flounder and yeloweye mullet are also common in the lower reaches of the Waikouaiti River. The river also supports a locally significant brown trout fishery, and is especially well known for its population of large sea-run brown trout in its lower reaches.

During the summer there is weekly monitoring at Bucklands. See the Otago Regional Council website for details.

Sites 2

Monitored sites in the Waikouaiti River catchment

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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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