Canterbury environmental officials are investigating a spill that has turned the Heathcote River blue.
Environment Canterbury's pollution staff are investigating the spill of about 40 litres of blue ink into the river from Mainstream Freight Group near Parkhouse Rd industrial zone today.
The spill occurred around 7pm last night but the ink did not make its way into the river until early today.
Environment Canterbury said reports suggested the ink spilled from two 20-litre pails at the freight firm.
An investigation is under way into how the ink escaped the company's sump/spill storage system and got into the stormwater system leading to the river.
The first complaints that the river was discoloured blue came after 9am.
Reports from the public indicated fish in the river appeared to be unaffected so far, Environment Canterbury said.
Industry sources have indicated that the ink may be inert, soluble in water and not toxic to fish life.
The ink has also been diluted by the amount of water in the river due to rainfall.
