Environment Canterbury is promising to find out why a popular swim spot is again contaminated and keeping people out of the water.
Corsair Bay in Lyttelton Harbour has again been rated as poor by the regional authority.
Science Director Tim Davie said while the site is tested once a week over the summer, the grading is based on five years of data.
“We have to put the health of the community first. Contaminated water has serious health risks - especially if it contains human faeces which is what we have found in some of the bays in Lyttelton Harbour.
“After consulting with the Medical Officer of Health we decided the safest course was to include samples from all-weather types including rain. On a hot day people will swim regardless of whether it rained in previous days, people may also not know about rainfall if they have just arrived in Christchurch,” said Davie.
Swim coach Dan Abel has cancelled his weekly swim race at Corsair Bay as he worried he would be held liable, after hundreds took part in the weekly event last year.
He said he had carried out his own testing which showed the water was safe to swim in, but refused to test it after rainfall like Environment Canterbury does.
Abel said people know to avoid beaches and bays when it rains due to contamination from the land, and he thinks the regional authority shouldn’t be testing then.
Davie said water quality is worse 48 hours after rainfall and that is important to know, however, these particular bays have also had poor water quality results in dry weather.
“The grades are based on an assessment of five-year datasets, that is because there is a delay between a sample being taken and a water quality result being available.
“Water quality changes quickly, it takes at least 48 hours in between water being sampled, transported and results processed by a lab.
“We need to consider people who are more vulnerable like those who are immune compromised, elderly or very young. They need the best information about the risk of getting sick by entering this water. One test from 48 hours ago will not do that,” said Davie.
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