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Harbour Water Quality Monitoring Programme

In 2009-2010, the Council added the Kaipara and Hokianga Harbours to its routine water quality monitoring programme, which brings the total number of harbours monitored across Northland to five.

In 2009-2010, the Council undertook routine water quality testing at 16 sites in the Whāngārei, Bay of Islands and Hokianga Harbours, and nine sites in the Whangaroa and Kaipara Harbours. Monitoring sites in these harbours have been selected to capture the main freshwater inputs into the systems, and to assess water quality across the harbour.

Water samples were analysed for physical properties such as temperature, salinity and turbidity – how clear the water looks – and for chemical parameters such as nutrients (ammonia, phosphorus and nitrogen).

Bacteria present in the water were measured using Enterococci, faecal coliforms and E. coli, which are indicators of faecal contamination. The New Zealand Marine Bathing Study showed that Enterococci are the indicator most closely correlated with health effects in New Zealand marine waters. Faecal coliforms are not as closely related to human health effects however they are useful in environmental circumstances, such as brackish or estuarine environments, where levels of Enterococci may occur naturally in mangrove forests.

Freshwater inputs from rivers are tested for the indicator bacteria Escherichia coli (E. coli). This bacterium indicates faecal pollution and scientific studies have shown that where E. coli is present, we can assume there are pathogens in the water. Water samples were tested for E. coli in harbours with large freshwater inputs. In the Hokianga, shellfish samples were also tested for E. coli at four sites.