A $4 million restoration project for the Mahurangi River started last month after almost 10 years of planning and negotiation.
Auckland Council has granted the Mahurangi River Restoration Trust a 33-year resource consent to dredge the river, from the town basin to Dawsons Creek.
The work is likely to take three years, depending on funding, and will result in the removal of more than 110,000 cubic metres of silt to create a 15-metre wide channel with a minimum depth of 1.5 metres below mean low-water spring tides.
The dredged material will be disposed of on low-lying farmland along the river or used to rebuild areas of the riverbank to enhance public access.
The restoration trust was formed in 2014 by Jane Gifford trustees Peter Thompson and Hugh Gladwell, who were becoming increasingly concerned about the build-up of sediment and its impact on the navigability of the river.
“When the Warkworth Wharf was built, there was about a metre of water at the wharf at low tide,” they say. “Now there is a metre of mud.
“When the Jane Gifford was re-launched in 2009, it floated at all stages of the tide, but now sits on the mud at low tide where the river is little more than ankle deep.”
According to the Mahurangi Action Group, which supports the dredging programme, empirical evidence indicates that Mahurangi sedimentation loads are five to six times higher than prior to catchment deforestation, and are at least double the loads measured in catchments elsewhere in the Auckland region.
Mr Thompson says that if the dredging had not been consented, there was a real possibility that the Jane Gifford could no longer operate from Warkworth.
He is comparing the project to the Whangarei Town basin, which went from “a muddy backwater to a stunning feature of the town”.
“One of the key outcomes will be to re-establish the river as a valuable resource for the community.
“All-tide access to the river basin will offer greater recreational opportunities, both on the river and in the adjoining reserves. Many older people in the community can remember a safe and healthy river, where people used to be able to fish, swim and boat.”
The tug Clearwater and a barge have been purpose-built to operate within the confines of the river.
While securing the resource consent was a major step in the project, Mr Thompson says funding the work is the next hurdle.
An advisory board, chaired by former local body politician Penny Webster, has been established to oversee the operation, with fundraising as one of its main tasks.
Other members of the board are Messrs Thompson and Gladwell, One Warkworth Business Association chair Chris Murphy, Steve Burret, Robert Jones and Jim Dollimore.
Mrs Webster says a cleaner and navigable river offers fantastic possibilities for Warkworth.
“While the focus of this project is on removing the silt, it is part of a much wider initiative to improve the ecology of the river and encourage riparian planting,” she says. “We need people to buy into this.”
The trust thanked a number of local companies for their support during the resource consent process, including OPC Planning, Hutchinson Consultants, 4Sight Consulting, Clough & Associates and Buckton Surveyors. Local iwi were consulted, and the Rodney Local Board and Warkworth Rotary supported the consent application.
Funding sought to complete work
Apart from the initial preparation work, the dredging programme will depend on funding. The Advisory Board will approach funding institutions, but these bodies will expect to see a contribution from the community. Donations from the public would be greatly appreciated and can be made at ASB Warkworth; by direct credit to The Mahurangi River Restoration Trust account 12 3095 0034484 00; or by cheque to PO Box 343 Warkworth. The Trust will issue receipts on request for all donations, which are tax deductible.