8. Coastal Water Quality

Northland coast.


RPS Objectives

Northland Regional Council seeks to maintain and enhance coastal water quality in the region to ensure its long term suitability for a range of purposes.

· In estuaries and inner harbours this includes; aquatic ecosystems, contact recreation, aesthetic and cultural purposes.

· In other harbour areas and coastal beaches water should be suitable for the above purposes and also for gathering shellfish for human consumption.

· Open coastal water is to be maintained in its natural state.

In addition, the council seeks to reduce the quantity of contaminants entering coastal waters and minimise the impact of oil pollution.


· Sediment input from erosion caused by land use practices employed in forestry, farming and other earthworks.

· Nutrient and bacteria input from farming, septic tanks and wastewater treatment system discharges.

· Metals and biocides input from boat maintenance and construction.

· Sewage from recreational vessels.

· Re-suspension of contaminants already in harbour sediments.


· In open coastal sites water quality is usually very high and maintained in its natural state.

· In harbour areas and coastal beaches, water is usually suitable for the purposes listed in the policy objectives. However, after heavy rain water quality is often not suitable for shellfish gathering or swimming due to bacterial levels. Sewage spills in the Whangarei Harbour and the Bay of Islands are causing concern for residents and marine farmers.

· In estuaries and inner harbours water quality depends largely on catchment land use and the tidal flushing characteristics of the inlet. In most cases water is suitable for swimming in fine weather but may not be after heavy rainfall.

Doing well

· Overall microbiological water quality is good in Northland with 52 of 55 monitored bathing sites passing the microbiological guideline (MFE 2002) on 90% or more of sampling occasions from 2002 to 2007.

· Water and sediment quality in Whangarei Harbour, particularly in the upper harbour has improved over the last 20 years.

Areas for improvement

· Few of Northland's many harbours are monitored on a regular basis and little is known about nutrient concentrations in Northland harbours and the effects of land use on this.

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Published: 03 Apr 2008