River Quality
There are nearly 19,000 kilometres of permanently flowing streams and rivers across the region. Most of our streams are short and narrow, draining quickly to the coast. The largest river systems in the region include the Hōteo River which flows to the Kaipara Harbour, and the Wairoa River which flows to the Hauraki Gulf. The topography in Tāmaki Makaurau forms rivers and streams that are typically slow flowing and low gradient, with predominantly soft stream beds. Hard-bottomed streams are mainly found in the Hunua and Waitākere ranges and on the Gulf Islands.
Freshwater systems are inherently interconnected, flowing from the mountains to the sea (Ki uta ki tai). This means our actions in one part of the system, such as on land, affect other parts of the system, flowing through our groundwater, rivers and streams to our coastal waters. Water quality can be affected by land use activities, discharges, land and stream channel erosion, as well as seasonal and climatic variability. Water quality affects the rivers capacity to support healthy ecosystems.
River water quality monitoring measures physical, chemical and microbiological variables that can be affected by land use activities, point and diffuse source discharges and land/stream erosion.
River ecology monitoring is undertaken to understand overall ecological health and condition. It includes monitoring freshwater invertebrates (e.g., insects, snails, worms, kōura) and fish living in streams as well as the types and quality of habitat available to native plants and animals.
Several of these water quality and ecology monitoring sites are paired at the same location. Monitoring sites are fairly evenly distributed across the region, and across proportions of dominant land cover type including some reference streams in catchments within native forest. There is a greater proportion of monitoring focused on urban streams recognising the high impact of urban activities on rivers.
More information on other measures of water quality and river health are available in regional reporting such as information on fish communities, stream habitat values, metal concentrations, and continuous monitoring of dissolved oxygen.
Auckland Council
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