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Warkworth residents can look forward to the Mahurangi River buzzing with boats again next year as a $4 million dredging project reaches its final stage.
Mahurangi River Restoration Trust’s Hugh Gladwell says about nine months’ work remains, with an expected completion date of next July.
So far, 46,000 cubic metres of silt has been lifted out of the river and spread onto a farm near the river, where it is dried and buried.
The trust had hoped the project would be finished this year, but it has been delayed by lockdowns and seasonal rain, preventing the silt from being dried.
Hugh says the dredging has already made a difference to the river. Six kilometres of the eight kilometre stretch earmarked for dredging has been completed, allowing a depth of 1.5 metres at low tide.
The river has so far been dredged from the Wilson cement works to Dawsons Creek. The remaining stretch from the cement works to the Warkworth town basin, although shorter, is the most challenging. Hugh says surveys show that this segment of the river has the most sediment.
He expects that once the dredging project is finished, the river will need maintenance dredging once every three years, similar to the Whangarei town basin.
However, the estimated 100,000 cubic metres of extra water that will flow up the river as a result of dredging will help flush the river out.
“It took 150 years for the river to degrade to this point,” Hugh says.
He hopes that with ongoing riparian planting and Watercare’s work to divert its sewerage plant outfall from the river out to sea, the river will be clean enough to swim in.
“Older Warkworth residents will recall swimming in the river as children, and we should be able to do that again.”
Hugh thanked the Cookson family who have allowed the silt to be spread on their farm and have been patient with delays.
“They have lived with a mud heap on their farm for five years. We are extremely grateful to them for putting up with it and letting us finish.”
The river was historically a hub of maritime trade, but siltation caused by surrounding development has prevented all-tide access to boats, until now.
