Dirty river report card 'misleading'

One slant on the latest recreational freshwater quality report from the Ministry of Environment has 100 per cent of Northland rivers so polluted they are not safe for swimming.

Waterways with the worst report card for the level of bacterial contamination, such as E.coli, included Kerikeri Basin, Whangarei Falls and Lake Waro.

The Northland "findings" headed the list of shame printed in the New Zealand Herald earlier this month. The Ministry of Environment (MoE) report indicated half the sites tested in New Zealand were unsafe for people to swim in.

But Northland Regional Council said the impression that all Northland rivers or lakes were badly polluted was misleading.

The report was based on data from five years of samples taken by regional and district health authorities from 210 freshwater "beaches" in New Zealand.

An MoE official said the sites were generally chosen for their susceptibility to risk factors.

"It focuses on the suitability for swimming at popular swimming spots, and does not give a comprehensive picture of the overall state of New Zealand's waterways."

Massey University ecology lecturer Mike Joy said the results showed that a clear difference between good and bad sites related to whether they were upland or lowland. All the downstream sites failed because of run-off from dairying and effluent from wastewater plants.

But NRC senior monitoring manager Colin Dall said it was not that clear-cut.

"Although farm run-off may well contribute to poorer water quality in lowland rivers, it is not the only cause."