Key Points | Report Card | Technical Information | Data
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What is happening in our region
Environment Waikato monitors invertebrates (such as insects and snails) in rivers and streams at sites across the region. The presence and numbers of these invertebrates provide indicators of the rivers' and streams' ecological health. This is because different invertebrate species have different tolerances to environmental stress.
This invertebrate sampling shows us that ecological health of streams and rivers is better in some parts of the Waikato region than in others. This is mainly because of the greater intensity of land use in parts of the region with large areas of lowlands and developed hill-country.
The following conventions apply for the graphs below.
- The ecological health of streams is grouped into 'excellent', 'satisfactory' and 'unsatisfactory'.
- 'Undeveloped' sites are those with catchments that have more than 90 per cent of their area in unmodified vegetation.
- 'Moderately developed' sites have 51-90 per cent of their upstream catchment area remaining in native forest.
- 'Highly developed' sites have 11-50 per cent remaining in forest cover.
- 'Very highly developed' sites have less then 10 per cent of their catchment remaining in forest cover.
- Urban sites are all located within Hamilton city.
- The ecological health data for different parts of the region are from sites sampled over 2002-2008. The data presented by land use development are averages from 2005-2008 when the sampling programme was re-designed to address this question (see the technical report: Review of Environment Waikato's regional ecological monitoring of streams).
Ecological health of the Region’s streams declines progressively with increasing levels of catchment development, and was lowest in urban catchments. Urban streams are influenced by stormwater, and sensitive invertebrate species are not usually found where the area contributing stormwater to a stream exceeds a particular level.
Habitat quality declines markedly with catchment development and is lowest in streams draining catchments almost entirely developed for agriculture. Lower habitat quality is mainly because of the lack of riparian forest cover and increased bank erosion along streams in developed pastoral catchments, although it can also partly reflect the low gradients of many lowland sites. Habitat quality is rated higher in urban streams than in highly-developed pasture streams because many streams in Hamilton city flow through vegetated gullies.
Ecological health and habitat quality have remained consistent over the last four years at sites draining catchments with agricultural development.
- Graph data were collected from 2002 to 2008. View the graphs' data.
- Find out more about river biology.
Why river biology is important
Our rivers and streams are under pressure from human activities. Water extraction, effluent discharges and vegetation clearance all change the physical and chemical environment in and around waterways. This affects the water and habitat quality of rivers and streams.
Environment Waikato monitors rivers and streams in the region to determine the extent to which ecological health has been damaged, see whether this is changing over time and to find out how successful remediation and mitigation activities have been.
Monitoring invertebrates helps us identify the state of and the significant pressures on freshwater ecosystems within the Waikato region. Invertebrates are part of the biodiversity in our waterways, form an important part of the food chain in rivers and streams, and can influence water and habitat quality by filtering the water, moving fine sediments and breaking down organic material.
What Environment Waikato is doing
- We track changes in the ecological health of rivers using invertebrates to update this indicator and to assist policy making and consent decisions.
- Environment Waikato has classified different waterbodies into different management classes. We have established these classes to manage water use and protect water quality values.
- Environment Waikato manages and requires the monitoring of resource consents to take water or discharge wastewater to rivers, or to dam or divert rivers and streams.
- We support voluntary guidelines and codes of practice such as the NZ Fertiliser Manufacturer’s Research Association’s Code of Practice for Fertiliser Use.
- We support care groups in the region that are involved in riparian management such as planting and fencing.
- We work with teachers to provide workshops and field trips focused on examining stream health.
Find out more about the water provisions in our Regional Plan.
What you can do to help
- Don’t put rubbish or harmful chemicals down stormwater drains – these drains run into rivers and streams.
- Avoid spraying insecticides when rain is expected.
- Don’t clear non-nuisance vegetation along stream banks. Shade is important.
- Keep stock out of rivers and streams and don’t let them trample banks.
- Join or form a care group in your area.
More information
More detail on this indicator, including how and where Environment Waikato collects this information, is available in the Technical Information page.
Useful links
Find out more about the state of our region’s rivers and what aquatic plants and animals live there.
For more information on aquatic species identifications and distributions see the NIWA and Landcare Research websites.
The United States Environmental Protection Agency website provides information on rapid bioassessment protocols for use in streams and wadeable rivers.