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The way Southland shellfish monitoring sites are tested has changed.
A decision was recently made to reallocate resources to improving water quality, rather than following up on known issues monthly.
Environment Southland (ES) science manager Elaine Moriarty said shellfish sites would now be assessed after three years’ improvement work.
"As opposed to going out every month and saying, ‘yep, it is still red’."
Results had been consistent, she said.
This time last year, a report was released from 2016-17 which stated shellfish from only one of eight gathering sites in Southland was safe for human consumption.
ES used to post results of shellfish sites to its website, but since the approach changed it listed only swimming sites.
The testing change did not affect the weekly summer monitoring of recreational water quality sites, several of which overlapped with shellfish sites.
The first results of the summer season should be ready in the beginning of December.
Dr Moriarty said the method for testing had been developed about 30 years ago, and it had been recognised it did not provide a good overall picture.
"We don’t have a lot of confidence in the validity of the method."
She was unable to provide a figure on the cost of resources spent on monthly testing.
Her advice was for people was to be aware of the environment they were in.
An example was to not swim or collect shellfish after heavy rain, or when people could not see their toes in knee-deep water.
Water quality was affected mainly by farm runoff, discharge and birds.
Research showed avian pollutants were a big factor in water degradation in Southland.
Across the country, work was under way to introduce predictive modelling.
"You can imagine we would say, ‘right, based on the weather forecast, what we know in the area, what discharges we know,’ we would create a computer model that would be able to give a predictive value."
Dr Moriarty suggested cooking shellfish and following food preparation guidelines to minimise health risk.
Information on swimming sites can be found on the Land Air Water Aotearoa website (www.lawa.org.nz) or through ES.