We value our waterways. Surface water quality is essential for supporting ecosystems, recreation, cultural values and the health of residents.

Minimum water flows in streams and rivers are necessary to protect the health of waterways and safeguard drinking water supplies.

What this means for our district

  • Water quality in our rivers, streams, lakes, and wetlands progressively improves
  • Waterways and beaches are safe for recreation
  • An increasing proportion of our waterways support mahinga kai

How we are contributing

Our storm water drains empty into rivers and streams. Storm water runoff is the chief driver of water quality in urban areas. Council is committed to improve our practices and lead by example to reduce pollutants getting into our waterways. A number of storm water management plans seek to manage surface water and drainage issues. Education campaigns are planned to show how the community can work together to improve our waterways.

Council is a co-governor of the Whakaora Te Waihora (Lake Ellesmere) programme (external link)which seeks to improve water quality and restore significant cultural sites and mahinga kai in the area.

How you can help

Keeping toxins out of storm water is one of the best ways to help water quality in our streams. Ask your mechanic about switching to copper-free brake pads next time they need replacing. Copper from brake pads gets washed off roads and into drains which then pollute waterways. Wash your car on the lawn rather than on the driveway to avoid detergent running into the drains. Pick up rubbish you see near waterways to stop it blowing into the water. If your old zinc roof needs replacing, use different products that avoid zinc runoff into our drains and waterways.

How we are doing

Status What do we want to achieve? What has happened?
Mixed
results
Indeterminate Result
 

Quality of Christchurch waterways

Since 2013 fewer sites are rated as poor and more have moved to the fair category of the Council's water quality index.

In 2017, 40 per cent had ‘poor' water quality, 40 per cent had ‘fair’ water quality and 19 per cent of sites had ‘good’ water quality. Further information.

Mixed
results
Indeterminate Result

Trend in water quality parameters in Christchurch rivers

Trends to 2017 show 26 per cent of river sites had improved water quality for specific parameters.

During the same period, 6 per cent of sites and parameters had a decline in water quality. Further information.

Mixed
results
Indeterminate Result

Avon Heathcote Estuary/ Ihutai water quality index

Around half the sites sampled had poor or very poor water quality, while the proportion with good or very good water quality appears to have decreased. Further information.

Negative result
NegativeResult

Lake Forsyth/Te Roto o Wairewa and Lake Ellesmere/ Te Waihora water quality

Lake Forsyth/Te Roto o Wairewa and Lake Ellesmere/ Te Waihora both have very poor water quality and are considered supertrophic.

Lake Forsyth/Te Roto o Wairewa looks to be improving. Further information.

Mixed
Results
Indeterminate Result

Contact recreation at Christchurch and Banks Peninsula rivers and beaches

All beaches in Christchurch, Lyttelton and Banks Peninsula were considered suitable for contact recreation over the 2016/17 summer.

57 per cent of sites in the Avon Heathcote Estuary and 25 per cent of river or lake sites in urban Christchurch were considered suitable. Further information.

Quality of Christchurch waterways

Since 2013 fewer sites are rated as poor and more have moved to the fair category of the Council's water quality index (WQI). In 2017, 40 per cent, 40 per cent and 19 per cent of sites were recorded as having ‘poor’, ‘fair’ and ‘good’ water quality, respectively. No site had ‘very good’ water quality, as guidelines were exceeded on at least one occasion at all sites. There was also no site that recorded ‘very poor’ water quality.

The Ōpāwaho/ Heathcote River and Linwood Canal catchments generally had ‘poor’ water quality. All other catchments generally had ‘fair’ to ‘good’ water quality. The Ōtūkaikino River recorded the best water quality out of all the catchments and the Ōpāwaho/Heathcote River catchment recorded the worst water quality, with the 11 worst sites all being from this catchment.

The best site for water quality was tied between the Ōtūkaikino River at Groynes Inlet and Waimairi Stream, followed by Wairarapa Stream in second, and the Avon River at Carlton Mill Corner and Avon River at Mona Vale tied for third. The worst site for water quality was Haytons Stream at Retention Basin, followed by Curletts Road Stream at Motorway and Curletts Road Stream Upstream of Heathcote River.

The Ōtākaro/ Avon River has showed an improvement in WQI over time, with the median WQI moving from the ‘poor’ category into the ‘good’ category in 2016 and then back down to the ‘fair’ category in 2017. The Ōpāwaho/ Heathcote River has shown no improvement in WQI over time, with the median WQI always within the ‘poor’ category.

The Huritini/ Halswell River in the last two monitoring years have showed an improvement compared to previous years, with the median WQI moving from the ‘poor’ category into the ‘fair’ category in 2017. The Pūharakekenui/ Styx catchment generally recorded an improvement over time, with the median WQI moving from the ‘poor’ category to the ‘fair’ category. The Ōtūkaikino River has been variable WQI scores over the years, with the median WQI moving between the ‘poor’ and ‘very good’ categories. The Linwood Canal has shown some improvements over time, with the median WQI predominantly in the ‘poor’ category.

Note the Huritini/ Halswell River, Ōtūkaikino River and Linwood Canal have a small number of sampling sites (three or less) in these catchments, as a consequence the monitoring may not be a thorough representation of the catchment water quality.

Trend in water quality parameters in Christchurch rivers

Trends in water quality parameters to 2017 show that over most parameters and sites selected have shown so significant change in parameter quality (69 per cent).  26 per cent of parameter-site combinations have shown increases in water quality and only 6 per cent have shown a decrease in water quality.  Although these changes do not take into account whether the parameter is meeting its guideline or not.

Parameters that had sites with decreasing water quality trends include E. Coli with 23 per cent, dissolved inorganic nitrogen(DIN) with 12 per cent, total ammonia and dissolved zinc with 7 per cent of sites getting worse across all catchments.

Biochemical oxygen demand (BOD5) and dissolved reactive phosphorus (DRP) showed the greatest improvement with 82 and 73 per cent of sites respectively.  These are followed by DIN with 45 per cent of sites improving.

The sites largest increase in parameter concentrations (decreasing water quality) were:

Whereas the sites with the largest decreases in parameters (improved water quality) were:

  • In the Heathcote catchment, dissolved lead at the Halswell retention basin outlet and Cashmere Stream at Worsleys Road reduced by 102 and 52 per cent respectively.  While Curletts Road upstream of the Heathcote River had a decline of dissolved copper of 56 per cent.
  • Dudley Creek in the Avon catchment had concentrations of dissolved lead decline by 49 per cent, and Knights stream in the Halswell catchment had reductions of 45 per cent in dissolved zinc and BOD5 .

 

 

Avon Heathcote Estuary/Ihutai water quality index

Water quality at 11 sampling sites in the Avon-Heathcote Estuary/Ihutai declined between 2014 and 2016, decreasing from 45 per cent to 18 per cent of sites having good or very good water quality (from 5 to 2 sites out of 11). This has resulted in an increase in the number of sites classed as fair.

The proportion of sites classed as poor or very poor has been around 45 to 55 per cent (5 to 6 sites out of 11). Sites located closest to the sea tended to have better water quality than those closest to the rivers and streams discharging into the estuary.

Note, this is based on 3 years worth of data, so it is not known if this is a trend in declining water quality or just normal annual fluctuations.

Lake Ellesmere/Te Waihora and Lake Forsyth/Te Roto o Wairewa water quality

Lake Ellesmere / Te Waihora and Lake Forsyth/ Te Roto o Wairewa have very poor water quality and are considered supertrophic (saturated in phosphorus and nitrogen).

In recent years water quality appeared to be improving, although in 2014 and 2015 Lake Ellesmere / Te Waihora water quality worsened and has returned to 2009 levels.

Lake Forsyth/ Te Roto o Wairewa has generally had improved water quality since 2010, however it is still classed as very poor quality.

Contact recreation at Christchurch and Banks Peninsula rivers and beaches

Since 2012, all beaches in Christchurch, Lyttelton Harbour and Banks Peninsula have been considered suitable for contact recreation, such as swimming, during the summer period in which sampling took place (November to March).

Only one of the four rivers or lakes sites in urban Christchurch was considered suitable for contact recreation, and this was Lake Roto Kohatu.

The Avon-Heathcote Estuary/Ihutai between the summers of 2012/13 and 2014/15 had 83 per cent of sites assessed as suitable for contact recreation. This declined to 67 per cent the following summer, before declining again to 57 per cent in 2016/17 when an additional site was added. If this site was excluded, the proportion of sites would stay at 67 per cent.

More detail and information

Council Surface Water Monitoring Reports:(external link) More detailed reports on the Council's surface water monitoring results and trends can be found on this page.  Water quality trend information and water quality index are from the latest report for the 2017 calendar year.

River catchment vision and values:(external link) These documents summarise the current status of, and key issues within, the river catchments relative to the Council’s six values of waterway asset management: ecology, drainage, culture, heritage, landscape and recreation. They provide examples of the surface water management approaches, or options available that might be implemented to as part of the stormwater management plans, to enhance the six values and realise the vision for the river catchments.

Environment Canterbury Water website:(external link) Contains reporting on the water quality and ecosystem health of waterways and the coast of Canterbury including reports on Avon-Heathcote Estuary/Ihutai. 

Land and Water Aotearoa website:(external link) This has information on water monitoring sites for the whole of New Zealand including water quality, swimming water quality, air quality and land cover.  It has detailed information for each site as well as how sites rate nationally.  This is regularly updated by regional councils.