Waikaia Gold has pulled the pin on its gold dredging operation in northern Southland, and is scheduled to finish in March.

The company has decided against going into a year-long fourth phase of mining.

During more than five years, Waikaia Gold has taken well over 2 tonnes of fine alluvial gold from about 150ha of paddocks near Freshford, a few minutes downstream from the township of Waikaia.

Mine manager Noel Becker, contacted yesterday, said a total of about 75,000 oz of gold was taken from the area by the 270-tonne purpose-built floating dredge, which sat in a pond and worked its way across farmland paddocks, at depths of up to 20m.

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''We're rushing headlong to oblivion; we'll be mined-out by March,'' he said.

The operation has employed 30-35 staff and contractors at various times.

A decision had recently been made not to mine a fourth phase of land, because of a combination of lower gold grades, the targets being a further 2m-3m deeper, the gold price being lower than expected, and extra costs associated with removing the overburden.

''That [fourth phase] could have given us another year's work,'' he said.

He said the company was looking at ''another couple of areas'' to mine, but declined to disclose where they were.

He said if mining elsewhere was not undertaken, the company would put the 42m long dredge, sheet piles and diggers up for sale.

The big haulage trucks belong to a contractor.

Waikaia Gold began in November 2013, as an $18million start-up, and within 22 months had gleaned its first tonne of gold from the farmland, at depths down to 16m-20m.

At yesterday's gold price of $US1284 ($NZ1899) an ounce, the total 75,000 oz would have been worth $US96.3 million ($NZ142.4 million).

Waikaia Gold's 42m dredge, fed by an 85-tonne excavator, working at a depth of around 16m at the start of the project. Photo / Supplied
Waikaia Gold's 42m dredge, fed by an 85-tonne excavator, working at a depth of around 16m at the start of the project. Photo / Supplied

In mid-2016 a gold production room, workshop and offices were destroyed in fire at the Freshford site, estimated at the time to have cost about $500,000.

In November 2015 a worker operating earthmoving machinery at the mine was killed and his employer, a Reefton-based earthmoving company, later admitted failing to ensure the safety of an employee.

That company was later prosecuted and ordered to pay $152,000 in reparations and fines.

When asked, Becker said there had been no major technical difficulties to overcome during mining, which required several kilometres of sheet-piling and water pumping, before mining could start.

''The operation will go flat out until the end, then turn to [land] rehab,'' he said.

A small ''lake'' has been left behind in a paddock near Freshford.

Becker said the paddock-bound ''lake'' was an amalgamation of several former dredge pits, and was consented for.

While the local farmer was not in need of an irrigation dam, Becker said the 4ha lake could become a community asset.

Land rehabilitation would continue after March, and depending on the weather, might not be finished until next summer.

Becker said while the mine permits went through to 2022, he expected they would be left to lapse.