| Graded fair or better | ||||
|---|---|---|---|---|
| 2023/24 | 2024/25 | |||
| River types | Number out of total | Per cent | Number out of total | Per cent |
| Alpine upland | 9 of 11 | 82% | 9 of 11 | 82% |
| Alpine lower | 6 of 7 | 86% | 6 of 7 | 86% |
| Banks Peninsula | 20 of 28 | 71% | 18 of 28 | 64% |
| Hill-fed upland | 20 of 22 | 91% | 21 of 22 | 95% |
| Hill-fed lower | 37 of 44 | 84% | 36 of 44 | 82% |
| Lake-fed | 0 of 2 | 0% | 0 of 2 | 0% |
| Natural | 5 of 5 | 100% | 5 of 5 | 100% |
| Spring-fed lower basin | 2 of 3 | 67% | 1 of 3 | 33% |
| Spring-fed upland | 7 of 8 | 88% | 5 of 8 | 63% |
| Spring-fed plains | 29 of 40 | 73% | 26 of 40 | 65% |
| Urban | 3 of 10 | 30% | 2 of 10 | 20% |
| Overall | 138 of 180 | 77% | 129 of 180 | 72% |
Healthy rivers provide for valuable ecosystem services and natural resources that sustain life. Rivers provide a home where native plants and animals can thrive, mahinga kai can be gathered, and a variety of recreation and leisure activities can be enjoyed. Fair or better aquatic ecosystem health contributes to the vitality of our rivers, streams, and communities.
Over time, urban settlement, rural development and long-term changes in how people have used the land have impacted Waitaha Canterbury’s waterways. Aquatic algal blooms and the spread of non-native aquatic weeds can lead to poor aquatic ecosystem health. This can impact land uses such as farming, and traditional practices such as mahinga kai gathering. Poor aquatic ecosystem health can also adversely affect the recreational use of rivers and streams.
Monitoring aquatic invertebrate communities (macroinvertebrates) is mandatory under the National Policy Statement for Freshwater Management (NPS-FM). We want to make sure our region achieves the desired freshwater outcomes, including for aquatic invertebrate communities in Canterbury’s rivers and streams. We also need to meet the resource management targets, limits and outcomes for our rivers specified in our Canterbury Land and Water Regional Plan (CLWRP).
Monitoring aquatic ecosystem health tells us about:
Environment Canterbury regularly monitors aquatic ecosystem health across the region at ~188 sites on different types of rivers and streams, such as alpine, or spring-fed urban, as managed under our CLWRP.
Aquatic macroinvertebrates are animals that lack backbones (“invertebrate”), are visible to the naked eye (“macro”) and live at least part of their life in water. Examples are aquatic dragonfly and stonefly nymphs, snails, worms, and beetles. Differences in their abundance and ability to tolerate pollution make them ideal indicators of river and stream health.
We analyse five years of data to determine the current year’s Aquatic Ecosystem Health (AEH) grades at monitored sites. We then compare these current year gradings with the previous year. Any changes over time can be tracked by comparing the changes in number/percentage of monitored sites graded fair or better from year-to-year. The overall proportion/number of sites graded fair or better can be reported for macroinvertebrates and habitat, including for different river types. Lowland and urban rivers tend to have poorer aquatic ecosystem health due to surrounding urban settlement and rural development. Monitored sites at higher elevations, away from urban settlements and intensive land use, tend to grade fair or better for habitat and invertebrate health.
To be consistent with other aquatic ecosystem health reporting in Aotearoa New Zealand, we use the quantitative macroinvertebrate community index (QMCI) for aquatic invertebrate assessments. For the river and stream habitat health assessments, we use the Rapid Health Assessment (RHA) (PDF file, 2.5MB).
As the regional council for Waitaha Canterbury, we work with ngā Papatipu Rūnanga and our communities to set and implement environmental policies and rules to manage freshwater, including for aquatic ecosystem health.
We advocate and support best land use management practices to minimise harm to waterways and help to improve aquatic ecosystem health in our region where it is poor.
Monitoring populations of aquatic macroinvertebrates, together with instream and riparian margin habitat health, helps us understand the impacts of habitat loss, pollution, or other environmental stressors in a river catchment.
Central government has set policy direction in resource management law for local authorities to manage impacts on freshwater, including rivers and streams, through the NPS-FM. Resource users, e.g. landowners, industries and manufacturing, are required to adhere to these laws, including rules set in our CLWRP.
Landowners and communities are working to minimise activities that disturb or damage the beds and banks of rivers and streams or cause water pollution. A priority is to manage riparian margins ki uta ki tai (from source to sea) to sustain aquatic ecosystem health.
In particular, landowners (public and private) with rivers and streams running through their land or on their boundaries have a role to play.
Recreational fishers and boaters can also help minimise impacts from habitat disturbance and pollution and avoid transferring or introducing invasive aquatic species.
Data for monitored sites are updated annually on the Land Air Water Aotearoa (LAWA) website and River Quality topic.
Methods for monitoring aquatic ecosystem health include: Macroinvertebrates » National Environmental Monitoring Standards (NEMS), and National rapid habitat assessment protocol development for streams and rivers (PDF file, 2.5MB).