A dredging project to improve the quality of water in New Plymouth's Pukekura Park has failed.
The New Plymouth District Council has stopped dredging the main lake at the park because it is clogging up with sediment, turning the lake dark brown, instead of cleaning it.
The dredging was meant to remove mud and silt from the water, and pump the clear water back into the lake, as part of a $2 million cleanup.
But the council's park manager Mark Bruhn says the process isn't working.
"The water's alot muddier than what it would normally be and certainly is not what we had anticipated it would be, so we are a bit unhappy at the moment."
Mr Bruhn says the contractor will be required to come up with an environmental remediation strategy to repair the damage.
He says the removal of sediment - up to a metre deep in some places - will not now be finished until next year.