Streams leading into seven of Northland's most popular beaches have been found to have high levels of pollution, the region's top environment watchdog says.
The Northland Regional Council says streams at Coopers Beach, two sites at Langs Beach (mid-beach and by the toilets), Ocean Beach, Otaua, Otamure Bay, Pacific Bay
and Whangarei Falls have poor water quality.
The council started a three-month water sampling at 63 coastal and 21 freshwater sites around Northland in December.
Results are being analysed and published on the NRC website every Friday and are also forwarded to the district councils and the Northland District Health Board.
NRC environmental monitoring officer Sophie Tweddle said the eight sites were on top of other water sources that have had poor results. Testing last week identified Matapouri (at second bridge) and Ngunguru (at toilets) as unsafe to swim.
In the Far North, Tinopai (below Puapua Creek), Pahi (150m northwest of the jetty), and Opononi were classified as potentially unsuitable for swimming.
Ms Tweddle said sanitary surveys were currently being conducted by NRC and the Whangarei District Council at Langs Beach, Ocean Beach and Pacific Bay streams.
These should identify whether faulty septic tank systems were a source of contamination, she said.
Ms Tweddle said faecal source tracking was currently being undertaken at Coopers Beach and Pacific Bay streams.
"Faecal source tracking gives us an indication of which animal faecal contamination has come from, for example, pigs, herbivores [such as cattle], possums, ducks or humans.
"It can also indicate whether or not contamination is a result of natural processes, such as the breakdown of organic material through decay.
"If a source of contamination can be identified, the council [NRC] can work with the local community, and where appropriate, local landowners, to improve the water quality in these areas."
In the case of Ngunguru toilets, the WDC was currently undertaking an investigation to try and establish the source of contamination, she said.
Ms Tweddle said most of the coastal swimming sites in Northland had good water quality most of the time.
Bacteria levels at the eight sites fluctuated.
Langs Beach tended to be the highest, she said.
