A discharge of partially treated wastewater has occurred from the Martinborough Wastewater Treatment Plant.
We estimate that about 90,000 litres – three rainwater tanks-worth – of partially treated wastewater entered the Ruamahanga River over a 12 hour period between 9.45pm last night and 10am this morning.
This is about two litres a second, or a dilution factor in the river of about 10,000 to one. Public health and recreational water user risk from the discharge is understood to be negligible.
Discharging treated wastewater to the river is a consented activity under the right conditions, but in this case, the discharge was not in accordance with the consent.
Another 45,000 litres of partially treated wastewater was discharged to land adjacent to the treatment plant, where treated wastewater is normally spread by irrigation.
Authorities at Regional Public Health and Greater Wellington Regional Council as well as iwi and community liaison group representatives have been notified.
We have initiated a full incident response and investigation and the outcomes of this work will be released when completed.