Nature or nurture for inlet?
inlet, while remaining safe.
He recounted how a young sailor smashed his front teeth when he hit the sandbar near Browns Bay – a particularly tough one to navigate.
He told Kapi-mana News last week that while the DHI report was still to be discussed by the PBC committee, they had been in favour of limited dredging of this sandbar.
‘‘It’s a narrow channel and from a safety point of view, we need to be Dredging Pauatahanui Inlet has been described as ‘‘ literally throwing $5 million into a hole’’ but at least one organisation does not believe the option should be discounted.
Porirua City Council and Greater Wellington Regional Council commissioned research group DHI Water and Environment to investigate whether localised dredging in the inlet would improve the flushing of the estuary’s mud and sand. Its report – available on the PCC website – found tidal speeds would have to increase considerably to enable sediment and sand to be flushed out and that dredging would not assist this.
This is also the same scenario for the Onepoto arm of the harbour, according to other advice PCC received.
The DHI report follows a hearing held late last year on the Porirua Harbour and Catchment Strategy and Action Plan.
Four submitters promoted dredging the harbour.
Paremata Boating Club ( PBC) commodore Paul Pettit told the hearing that access and navigation were key to members enjoying the
To dredge or not? The issue has been put to bed in politicians’ minds but members of the sailing community want the door left open. able to get rescue boats in there quickly sometimes. Personally, I think closing the door on it [dredging] now depends on what the inlet’s going to be like in the future. If you can stop the sedimentation buildup, cool, but if in 30 years time it hasn’t been stopped, do you revisit dredging?’’
The DHI report gives two options for controlling sedimentation – dredging, which will only ‘‘maintain the harbour’’, or controlling what comes into the inlet from the catchments.
Regional councillor Barbara Donaldson says GWRC supports sustainable land management and ecological restoration to aid in the fight against sediment buildup.
‘‘We can’t stop it altogether – it’s a natural process.
‘‘ However, it’s currently happening much faster than it should and must be reduced if we are to succeed in revitalising the harbour.’’
DHI predicted the channels were likely to fill with sand ‘‘ reasonably quickly’’ even if dredging was carried out. One, off the end of Seaview Rd, would cost $800,000 to dredge and $4m to dispose of the sand.
Porirua Mayor Nick Leggett is unequivocal on the issue.
‘‘ It would be literally like throwing $ 5m into a hole that would be ineffective and eventually refilled with sand.
‘‘People need to understand that this is not Lake Taupo – it’s a tidal estuary that’s constantly moving, and sandbanks and mudflats are normal. This [DHI] report firmly shuts the door on localised dredging.’’