It's not yet known how much toxic oil has been flushed into Kaiapoi rivers or the extent of ecological damage following a major factory blaze.
A Sunday morning fire that destroyed the Sutton Tools manufacturing plant caused quenching fluid, which is used to rapidly cool steel, to be flushed through the stormwater network.
Environment Canterbury's coastal response and readiness lead Emma Parr said while it was difficult to estimate, it was likely "thousands" of litres of the oil had been flushed since the fire broke out.
"They know how much they had, so when they remove what's left we should be able to come up with an estimate of what has left the site."
Parr said that the initial flush of oil from water used to extinguish the blaze was in the early hours of Sunday morning.
It went through stormwater networks and into rivers heading out to the mouth of the Waimakariri River.
The first flush would have sent the toxic oil to the sea via the rivermouth, Parr said.
By yesterday afternoon, the oil was only coming up as a "light sheen" across the Cam / Ruataniwha and Kaiapoi Rivers.
A sucker truck was on site yesterday and several booms to collect oil, 1100 litres of which were able to be removed.
Parr said the truck would be operating again this morning.
It is also not yet known the extent to which the oil leak has damaged the natural environment around the riverbeds and sea.
"We don't know the exact negative impact [the oil] will have on fish, or wildlife, or the environment at this stage," Parr said.
ECan will be undertaking ecological assessments of the area over coming days.
"Because it is an oil, it floats on the surface of the water, so it doesn't affect the riverbed, however, it is clinging onto the vegetation of the banks and the mud."
However, because Kaiapoi's rivers are tidal, the oil is moving up and down the riverbed.
More field assessments will take place today along the rivers, and a new recovery plan will be made.
Parr said it is tough to say how long the cleanup operation will take, but ECan will be monitoring the area in the coming weeks.
Meanwhile, fire services are working with investigators to try understand what caused the blaze.
Residents from up to 40 nearby houses were evacuated to a school when flames took hold.
Waimakariri mayor Dan Gordon told Morning Report he was not aware of any risk the business would move out of the town.
"It's been in our town for 60 years, so it's a huge impact to have a business like this gutted and destroyed. There are some parts of the factory, newer part of the factory which still remains."
He had no information whether jobs would be affected.
"If I need to, I'm happy to get on the phone and talk to the Australian owners to convince them to remain here.
"Myself and our council will do everything we can to make sure we keep those jobs here and also keep this business here."