Water quality in our monitored rivers and streams
The water quality in monitored rivers and streams is graded good or very good.
For 2018/19 the water quality in 37% (38 out of 104) monitored sites was graded good or very good.
About this goal
Protecting and improving freshwater quality is one of Environment Canterbury's key roles which starts with an effective and widespread monitoring programme.
Why does it matter?
Urban settlement and rural development have, over time, caused a decline in the water quality and ecosystem health of many of our rivers and streams.
Poor water quality affects native plants, animals, and ecosystems as well as human health. As a result, we have put in place solutions to better manage our land-use and the impacts on freshwater and ecosystems.
What's being done?
Environment Canterbury is working with the community to ensure we have clean and plentiful freshwater now and for generations to come – but the impact of human activity will take many years to repair. People from across our region are working together to protect and improve our water resources.
Find out about what's happening in your local water zone. Actions are in place to lessen impacts on waterways. Priorities are to:
- Reduce contaminants that impact freshwater quality (nitrogen, phosphorus, sediment, and microbes such as Escherichia coli (E. coli).
- Improve how we manage riparian margins (fencing and planting).
How we are tracking?
Each month we collect and analyse samples from a network of 104 monitoring sites across Canterbury to build an understanding of the state of our freshwater resource.
We test for several geochemical, bacterial and physical attributes that are combined into a Water Quality Index (WQI). The WQI is assessed on a five-point system: very good, good, fair, poor, very poor. Sites monitored vary from year to year.
Christchurch City Council calculates their own WQI for Christchurch urban streams.
Alpine rivers, which are typically in catchments mostly unaffected by human land-use, have very good water quality. As we move eastwards and down the Canterbury Plains, streams and rivers begin to suffer the effects of intensive land-use from both urban and rural areas. Upland hill-fed streams, for example, have mostly good water quality (7 out of 10 good/very good), but spring-fed streams have much poorer water quality as a result of the effects of intensive land-use.
Changing weather patterns and climate can also influence the WQI from year-to-year.
What are the water quality parameters used in the WQI?
- Nitrate-nitrite nitrogen (NNN) for toxicity
- Dissolved inorganic nitrogen (DIN) for effects on periphyton and macrophyte growth
- Dissolved reactive phosphorus (DRP) for effects on periphyton and macrophyte growth
- Ammonia-nitrogen (NH4-N) for toxicity
- Total suspended solids (TSS) for effects on clarity and sedimentation
- E. coli for effects on suitability for recreation
In the graph below click on the individual grades (very good, good, etc) to turn them on or off and make it easier to understand the data.