By ANNE BESTON, environment reporter
Why 13,000 cubic litres of diesel fuel was deliberately spilled into one of New Zealand's most prized tourist spots remained a mystery yesterday.
Police were considering the possibility that the spill was an act of eco-terrorism linked either to the foreshore and seabed issue or the debate over whether Milford Sound is being degraded by too many tourists.
The diesel poured into the sound when a high-pressure hose was shoved into the fuel tank of Real Journey's 430-seater Milford Monarch, forcing the diesel to the top so it spilled out of the tank.
Last night, rain and high winds were forecast for Milford Sound and both were expected to help disperse the diesel.
Another 2000 tourists were again unable to cruise the sound yesterday, on top of a similar number on Sunday.
Environment Southland oil response leader Warren Tucker said a boom remained across the harbour and storage tanks held so much of the diesel-affected water and absorption material that disposal had become an issue.
The waste could be transported to Te Anau and stored there for possible re-use.
Staff had worked tirelessly to clean up the spill and were expected to work late into yesterday evening.
Mr Tucker was "95 per cent sure" the basin would reopen for normal cruise boat operations today.
Only a quarter of Freshwater Basin, where cruise boats dock, remained covered in a light rainbow sheen from the diesel fuel last night.
Some was detectable at Harrison Cove, with isolated pockets in the middle of the fiord.
Department of Conservation spokesman Reg Kemper said no wildlife injuries or deaths had been reported.
One possible outcome of the spill is that cruise boats in the sounds will have to lock their fuel tanks.
The Herald understands the cap on the Milford Monarch's tank was a screw-cap with no lock.
Southland Mayor Frana Cardno said that was probably one lesson that could be taken from the incident.
"It must not happen again. There has to be better security," she said.
Rival cruise operator Milford Sound Red Boat Cruises said both companies had pulled together in the crisis.
"It's been all hands to the pump. We have as much to lose as they do," said spokesman Richard Wilson. "We are disgusted by what's happened and my heart really goes out to Real Journeys. There is no evidence as to why it was them and not us."
He said capping tourist numbers to the sounds was an issue for the company.
DoC has included a proposal to cap tourist numbers to Milford Sound in its draft management plan for Fiordland National Park.
Mr Wilson said the company would fight the plan when hearings were held in two to three months.
* About 4000 tourists have been prevented from cruising the sound since the spill.
* A plan for sustainable development for the tourist icon may include a cap on the number of visitors.