Water supply testing after herbicide find

Press, 27 July 1988, Page 9

Water supply testing after herbicide find

The quality of Christchurch's drinking water will be tested after the discovery of high levels of a chemical herbicide in the Styx River. The survey by the North Canterbury Catchment Board had found quantities of the herbicide, Simazine, at 14 times the accepted toxicity level.

The survey was made after the North Canterbury Acclimatisation Society objected to an application by a Marshland orchard to discharge land drainage into the Styx River. The water would contain considerable amounts of herbicide, said the society. The Catchment Board then kept an eye on the orchard’s land drainage and discovered the high concentrations of herbicide, said a staff member, Dr Mike Freeman. The orchardist was ap-

proached and has since changed to another, less harmful, herbicide, but the discovery raised questions about possible contamination from other orchards which drained into the Styx River, said Dr Freeman. It also raised a concern about what could be happening to Christchurch’s supplies. If the chemicals were getting through into land drainage, it was possible they were also getting into the groundwater which supplied drinking water, he said. This prompted the Catchment Board to budget for a survey of Christchurch’s groundwater in September and October. It was unlikely high concentrations of pesticide would be found, but the board had a responsibility to check, Dr Freeman said.