Dead and dying eels were discovered near the stormwater outlet at the end of Grace Road, near Memorial Park in Tauranga last Monday.

The matter was reported to Tauranga City Council and a pollution prevention officer from both TCC and the Bay of Plenty Regional Council discovered between 40 and 50 short-finned eels near the outlet, many of which were dead or in a distressed state.

Dead eels were found near Memorial Park in Tauranga last Monday. Photos: Supplied.

Officers tested the water at the outlet before using a fire hydrant to flush fresh water into the pipe in an attempt to revive the dying eels.

The eels showed visible signs of burns which could have been caused by chemicals washed into the stormwater system.

'It's is a real shame to see this many eels, some of which were over a meter long and could be over 20-years-old, killed in this way,” says Taranga City Council's pollution prevention officer Radleigh Cairns.

'People need to be more aware of the fact that outside drains around houses and on the street are only for rain as they generally lead directly to the harbour without any form of treatment.

'Anything washed or spilled into these can have significant consequences for aquatic life.”

The water quality tests did not show anything out of the ordinary and it's likely that the chemical or pollutant had been flushed through by the existing groundwater flow by the time the incident was reported.

Officers searched the area but could not identify the source, however the catchment is residential and it is likely to have been a result of a spill or household maintenance by a homeowner or contractor.

'The eels appeared to have suffered from chemical burns and these could be a result of a spill of a chemical like chlorine, or cement wash-off which has a very high pH,” says Bay of Plenty Regional Council pollution prevention officer John Morris.

'Water-blasting using a chemical cleaner or acid washing could have also caused the eel deaths.

'It's important if people are undertaking DIY projects, or using contractors to do work around their home, that they know how to prevent pollution of waterways and the harbour.”

There were no more dead eels seen after a follow-up check at low tide today.

Homeowners or contractors who need advice on the safe use of cleaners and chemicals, and how to protect our waterways and harbour, can contact Tauranga City Council's Pollution Prevention Team on: 07 5777000.