No prosecution after discharge of algal bloom

The Gore District Council won’t be prosecuted for discharging an algal bloom into the Mataura River.

Late last year and early in 2019 Environment Southland received complaints from the public regarding discoloured discharges from the Gore and Mataura wastewater treatment plants.

Stuff reported in January that a bright green substance had been discharged from the Gore wastewater ponds in December, and another discharge was released from the Mataura wastewater ponds in January.

Environment Southland compliance manager Simon Mapp said the council had determined that both discharges came from algae produced in the wastewater treatment plants.

‘‘We carried out an extensive investigation, including in-depth analysis of samples, expert opinions and interviews with members of the Gore District Council wastewater treatment team,’’ Mapp said.

At the time, Gore District Council staff members said it was ‘‘relatively common’’ for algal blooms to appear in its wastewater ponds.

Mapp said Environment Southland’s investigation was now complete.

He said although initial signs and samples indicated that the discharge contained toxic algae, further analysis identified that cyanobacteria was already present in the river at the time and the results did not breach World Health Organisation drinking water standards, or Ministry for the Environment and Ministry of Health guidelines for bio volume or consent contaminants limits.

Cyanobacteria, also called green-blue algae, forms in rivers in warmer months and can be harmful to dogs.

Mapp said an independent legal opinion determined that a successful prosecution was unlikely. In accordance with the regional council’s policies and the Crown prosecution guidelines, a prosecution will not be taken.