Media release

E. coli in a Lower Waitaki Aquifer bore

Thursday 29 November 2018

Otago Regional Council (ORC) advises that elevated E. coli levels have again been detected in a bore feeding from the Lower Waitaki Aquifer.

Faecal source tracking from water quality testing on 18 October showed that a cow marker was present, meaning there is a likelihood the source of the E. coli is cattle.

The results show elevated E. coli at 41 MPN / 100 ml. The recommended level for safe drinking water is that there should be less than 1 MPN / 100 ml.

ORC Director of Science, Hazards and Engineering, Dr Gavin Palmer said, “additional testing is being carried out on nearby bores to see if the source of the contamination can be identified.”

Dr Palmer said, “We increased our water sampling from quarterly to monthly after the first results showed up in September and have built faecal source tracking into the monitoring programme.”

“We are also carrying out dairy inspections on all properties in the area and looking at irrigation practices during these inspections as part of our source tracking,” he said.

The same bore tested positive in September, when E. coli was 63 MPN / 100 ml and the source showed a high probability of being cattle.

It is recommended that Lower Waitaki Plains residents who source their drinking water from private bores should assume their source water is contaminated unless they have effective disinfection in place.


Media contact
Emma Schranz – ORC Senior Media Advisor