Hawke's Bay Regional Council has been forced to stop work on a Flood Control and Drainage scheme near Puketapu after dozens of dead eels were discovered on a nearby bank.
"As soon as we were made aware of this issue, work has been stopped until a full review of the standard work practice can be completed over the coming days," said Hawke's Bay Regional Council group manager Chris Dolley.
"There have already been discussions, and one of the options we are looking at is a catch and release option with local iwi, but we would need to speak with them to work out all the details of that."
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Mr Dolley says the maintenance of the drains is challenging, due to the size of the drain network.
"Every drain needs to be cleared out of sediment and organic matter every seven years to maintain the grade and capacity in the drains," he explained.
"We only carry out mechanical clearing of drains when it is required, as it is one of the most expensive components of our maintenance regime."
He says a slotted bucket is inserted into the digger, which allows water and eels to escape, but acknowledges it is not a perfect system.
"Sometimes, not all of the eels manage to escape this way."
The slotted bucket method has two processes - the first and preferred method is to place organic material on the bank of the drain, so that eels can be seen and return to the water.
The second, which was used in this instance, is to place the material directly into a truck.
"This is used if the drain is alongside a road, or orchards were placing material to the side of the drain is not possible."