Northland has a dense network of rivers and streams, many of which are relatively short with small catchments. The Wairoa is Northland's largest river, draining a catchment area of 3650 square kilometres.
Most of the major rivers flow into harbours, rather than discharging directly to the open coast. This has significant implications for coastal water quality. Flows in rivers vary considerably with rainfall, high intensity storm events causing flash floods and prolonged dry spells leading to very low flows in many smaller catchments. Overall, Northland's rivers are generally characterised as being slow flowing and muddy.
The Northland region also has a large number of small and generally shallow lakes. They are predominantly dune lakes, although there are also a few volcanic and man-made lakes. For more information on the state of Northland's lakes check out the lake quality section of this SOE report.
The Regional Policy Statement contains a range of objectives relating to the quality of Northland's surface freshwater resources. These objectives seek to maintain, and where possible improve, surface water quality in the Northland region.
The Regional Policy Statement objectives are:
· The maintenance or enhancement of the water quality of natural water bodies in Northland to be suitable, in the long term, for the following purposes as may be appropriate: Aquatic ecosystems, contact recreation, water supplies, aesthetic and cultural purposes.
· The reduction in the quantity of contaminants that impact on water quality entering lakes, rivers and streams.
The following is the anticipated environmental results after the implementation of the water quality policies in the Regional Policy Statement:
· Water quality suitable for desired purposes.
· Contaminants in water bodies reduced.
· The adverse effects of contaminants in water bodies and coastal waters be avoided, remedied or mitigated.
· That all existing discharges of organic contaminants be via the best practicable option for treatment and disposal by the year 2004.
· That all new discharges of organic contaminants be via the best practicable option for treatment and disposal.
· Improved aquatic habitat.