A spokeswoman for Auckland Council confirmed the cow had since been disposed of, "ie it's gone to landfill''.
Council contractors traced which farm the cattle beast was registered to via its ear tag.
The spokeswoman said the farmers would be contacted and told what's happened to their young cow.
"It's definitely come off a farm, probably from up the harbour around Paremoremo or further up to Coatesville where there's some farms that go down to the waterfront there,'' Mr Goff said.
Cattle occasionally fell off banks or cliffs, or got stuck in the mud of mangroves before getting swept away with the tide, said fellow duty officer Marc Davis.
Mr Davis said the cow, which they believed had been in the water for two to three days, "held up well under the tow, which is good''.
Mr Goff said another cow was reported floating in the harbour last month.
"You never know what you're going to fish out of the harbour. Nothing really surprises us any more,'' he said.
Mr Goff said the Harbourmaster team was often called upon to remove obstacles from the water, including spa pools, rafts, pallets, big logs, trees, roadside barriers, and fishing nets.
The more grim finds, like human bodies, were usually left to the police maritime team to deal with, he said.
The Coastguard said it issued regular warnings to the boating public about possible navigational hazards due to high tides.
Mr Davis said the debris floating down from the upper reaches could pose a real hazard to vessels once it went under the harbour bridge, especially for the ferries.
