Between 40 to 50 dead and dying eels were found near a stormwater drain in Tauranga.
Council received a report on Monday of both dead and dying eels near a stormwater drain at the end of Grace Road near Memorial Park.
Pollution prevention staff from both Tauranga City Council andBay of Plenty Regional Council attended the incident to discover 40 to 50 short finned eels near a stormwater outlet, many of which were dead and the rest in a very distressed state, said Tauranga City Council's communications manager Aimee Driscoll in a statement.
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.
The eels showed visible signs of burns which could have been caused by chemicals washed into the stormwater system.
Officers tested the water at the outlet before using a fire hydrant to flush fresh water into the outlet in an attempt to revive the dying eels.
"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." said Tauranga City Council's Pollution Prevention Officer Radleigh Cairns in the statement.
"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."
Water quality tests did not show anything out of the ordinary and it is likely 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 of pollution, however the area 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." said Bay of Plenty Regional Council Pollution Prevention Officer John Morris.
"Waterblasting using a chemical cleaner or acid washing could have also caused the eel deaths. It is important if people are undertaking DIY projects, or using contractors to do work around their home 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.
TCC encourages homeowners or contractors who need advice on the safe use of cleaners and chemicals, and how to protect local waterways and harbour to call Tauranga City Council's Pollution Prevention Team on 07 5777000.
