Erosion will become a significant issue

The Tasman District Council is between a rock and a hard place over Jackett Island erosion - or perhaps that is between quicksand and a very soft place.

A groyne the council built nearly 20 years ago on the northern side of Port Motueka's channel was found by the Environment Court to have caused significant erosion on Jackett Island to the south. The groyne, built to try to keep the port channel clear of drifting sand, was ordered to be removed, and the council did so last July.

The court also ordered the council to maintain a protective wall in front of one of the worst-affected properties, find a sustainable long-term solution to the continuing erosion, and pay $252,000 in costs to the Van Dyke Family Trust.

Last year the council raised hopes that its insurer would cover the damage caused by the groyne to the island. It started, and then cancelled, extensive computer modelling seeking appropriate solutions, and has chosen to challenge the court's findings instead.

Ratepayers will be hoping it has firmer grounds for doing so than the eroding lands and sands of Jackett Island. The issue has already carried a heavy cost to the council, and should the court's findings be confirmed, the liability will likely grow.

Meanwhile, a council report suggests that the erosion is "shifting further south", which potentially increases its exposure and the risk of fresh court action from other landowners.

The council says its latest modelling has shown that the 1996 groyne did not cause the Jackett Island erosion after all. This will give councillors hope, but the council will need more than that if it is to succeed in reversing the court's findings.

Its opponents will see the court challenge as nothing more than a cynical stalling action that might merely delay the inevitable, cost all parties significantly in legal costs and expert witness expenses, and allow the problems to grow.

Regardless of the complicity or otherwise of the groyne, the general - and much wider - issue of coastal erosion can be expected to increase, assuming that predictions of continuing sea level rises are on the mark.

The Tasman District Council will not be alone in facing significant challenges in either having to move or protect substantial assets located near coasts. Councils will be expected to consult widely with their communities and plan wisely if they are to reduce the impact of encroaching seas.

Tasman is being accused, not for the first time, of failing to consult adequately with affected Jackett Island landowners. While this can be difficult when legal proceedings, liability questions and substantial costs are involved, the greater the collaboration and frank, open discussion between disputing parties, the more likely it is that common ground and acceptable solutions will be found.

The council says cutting a channel through the fast-growing sandspit, and maintaining it for 35 years, will cost it $53 million. That seems an outlandish figure, and it is no wonder that councillors don't want a bar of it. Hopefully, opting to go back to court will not end up costing ratepayers even more.