High alert at wastewater treatment plant following overflow today

Heavy rainfall has resulted in a overflow at the Rotorua Wastewater Treatment Plant today. Photo/Ben Fraser

Heavy rainfall over the weekend has resulted in an overflow of the storage ponds at the Rotorua Wastewater Treatment Plant today.

Rotorua Lakes Council said the very high inflow into the plant exceeded the rate at which the plant was able to pump treated wastewater to the forest.

This resulted in treated wastewater storage ponds reaching capacity about 7am today and later overflowing intermittently via the emergency overflow pipeline to Puarenga Stream.

The overflow has since stopped with inflow to the plant decreasing and the ponds gradually emptying.

Council staff will continue to manage and monitor the situation to ensure everything possible is done to avoid any further overflows although forecasted rain this afternoon and for the next few days means the situation will be dependent on the amount of inflow and the plant's capacity to deal with it.

The overflow is treated wastewater which has been through full treatment and due to the rain contains a higher than normal amount of rainwater, diluting it further.

Water samples have been taken upstream and downstream of the overflow pipe in the stream but will take a day or so for the results to be received.

Bay of Plenty Regional Council has been notified and the council is also notifying relevant staff at Bay of Plenty District Health Board and Toi Te Ora Public Health.

As a general precaution people are advised to not swim in any waterways after substantial rainfall in case of pollutants, which can be washed into them from a number of sources.

Signs will go up in the Puarenga Stream and Puarenga Bay areas advising people not to swim.

Bay of Plenty Regional Council rain data showed Rotorua had 123mm of rain since Friday.

Rotorua residents can expect more rain during the next 24 hours with a new warning in place.

Heavy rain may cause streams and rivers to rise rapidly and surface flooding and slips are also possible so driving conditions may become hazardous and caution is urged.

The current warning for Bay Of Plenty, including Rotorua, is valid until 8am Tuesday with periods of heavy rain and possible thunderstorms forecast.