A Kaipara leader is calling for Kai Iwi Lakes to be closed to boating before Christmas as the threat of invasive freshwater gold clams grows.

Ric Parore’s comments come on the eve of Kai Iwi Lakes’ busiest camping season of the year.

The pest has spread from its Waikato River stronghold to Taranaki, more than 200km away.

Authorities say the Taranaki clams, found on November 2 by a member of the public near a Lake Rotomanu boat ramp, likely arrived via a boat from infected areas. The lake was closed to boating on November 12.

The invasive clam has the potential to clog boats’ engines and working parts – as well as dams, pumps and hydro-electric power station intakes.

About 7500 people will be camping at Kai Iwi Lakes over summer, and almost 19,000 visitors are expected to visit the lakes this year. Many bring runabouts, jet skis, kayaks, yachts and other watercraft.

Parore (Te Kuihi) said the Taranaki find increased the risk of the pest arriving in Kai Iwi Lakes, which authorities have already defined as being at risk.

He planned to discuss closure at a Northland Regional Council (NRC) Kai Iwi Lakes working party meeting in Dargaville on Thursday this week.

Dargaville’s Alan “Sonny” Nesbit (Te Roroa) said gold clams were the worst pest the dune lakes had faced.

Their spread from Waikato to Taranaki showed New Zealand’s biosecurity controls for the pest in that area were not working.

NRC deputy-chair Jack Craw said the regional council strongly advocated for a temporary ban on powered watercraft to safeguard the lakes, local businesses and surrounding communities.

“Powered watercraft pose the greatest risk because they are difficult to clean thoroughly.”

Craw said the Kaipara District Council (KDC) had voted not to support the ban.

That was despite strong mana whenua support, a recommendation from the council’s own Taharoa Domain governance committee – which sought closure from Labour Weekend until a government-controlled area notice was in place or an alternative solution found – and NRC advocacy.

Nesbit claimed the KDC was only interested in the lakes as a golden egg for raising money from the two council-owned campgrounds there at the expense of the lakes’ health.

He believed it was just a matter of time until freshwater gold clams reached Kai Iwi Lakes, which he said would “fall over” as the pest consumed nutrients and altered ecosystems.

The council and Biosecurity NZ want residents to follow “check, clean, dry” guidelines in an effort to stop the spread of the invasive freshwater gold clam, which has been declared an unwanted organism under the Biosecurity Act 1993. Photo / Horowhenua Chronicle

The KDC’s manager of community services, Glynis McCarthy, said legal advice the council had sought in June indicated it did not have authority under the Reserves Act to close Lake Taharoa boat ramp, and any decision to close the facility could be legally challenged.

She said the KDC had proactively sought to help the NRC by updating councillors, ensuring there was space at the boat ramp for education on clams, and that the NRC, Te Roroa and Te Kuihi educators had formal warranted authorisation.

However, frequent Kai Iwi Lakes visitor Gordon Gilmour, from Auckland, favoured the KDC’s decision to keep the lakes open.

With Rodney and Julie Field, of Omamari, he spoke against the closure at the KDC meeting where the decision about it was made.

Gilmour and his family visited Kai Iwi Lakes year-round from their Baylys Beach bach. They had two jet skis used only at Kai Iwi Lakes, so posed no clam spread threat, but Gilmour said more needed to be done to prevent the pest’s arrival at the lakes.

Rodney Field (Te Ītiawa) said that instead of closing the lakes, more effective prevention measures could deal with the matter.

He was pushing for a hot-water boat-wash station with air drying. “Cold water boat washing doesn’t kill the clams.”

Field offered to pay towards a joint venture to set up the station on land he owned near the lakes and had also offered for this purpose.

He recently visited Lake Powell, a major holiday destination reservoir on the Colorado River in the United States, to see boats’ clam prevention control technology in action.

Field believed the current boat checks at the lakes, plus education, signage and peak-season cold-water blasting for boats, were not enough.

Craw said the NRC had asked Biosecurity New Zealand in May to implement a controlled area notice (CAN) legal pest control tool for the lakes as an alternative, but had not heard back.

Biosecurity NZ’s head of pest management programmes, Dr Cath Duthie, told Local Democracy Northland that more information had been sought from the NRC and it would be considered when it was received.

“The risk that the invasive clam may spread from the Waikato River remains because the clam is a prolific breeder and can be easily spread by juveniles attaching to the surfaces of boats and water gear,” she said.

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