Up to 20,000 litres of light fuel oil spilled into the Liffey yesterday following a collision between an oil-tanker and a lorry on the N4 near Palmerstown.
Dublin Corporation removed swans and ducks downstream from the spillage and placed four booms across the water at Islandbridge to stem the flow of oil.
Polluted water was vacuumed using specialist equipment provided by the Depart ment of Marine and Natural Resources, the Dublin Port and Docks Board and Esso, whose oil was being carried in the tanker.
The city engineer, Mr Michael Philips, said: "Damage to wildlife seems to be minimal at the moment. There was no apparent fish-kill, and only a couple of ducks had oil on them. That may change, however, depending on the tide, and we will only know when it's all cleared up how serious the damage is".
A spokesman for Esso said it had adopted a pro-active approach to the situation. "We are doing everything possible to handle the spill."
The company, which had leased the Emo oil-tanker from contractors, established an incident management team to assist in the clean-up. On-site interceptors were put in place last night to separate the oil from water on the river bank, thereby speeding up the process.
A separate clean-up operation took place on the dual carriageway where sand and other absorbent materials were laid. Of 27,000 litres on board the tanker, 5,000 were recovered on site, according to engineers.
The company said the oil, which was designed for use in industrial boilers, was never in danger of catching fire.
It was estimated that the clean-up would take at least a week.
Last night concerns were expressed about strong currents that could cause the oil to break through the booms, causing further pollution downstream.
The slick was said to be a mile in length, stretching back to the Chapelizod bridge, where oil leaked through gullies from the road.
Traffic was reduced to two lanes on the Palmerstown bypass as a result of the accident, which occurred at 10.30 a.m. Outbound traffic was diverted until the road was cleared of oil.
The driver of the oil-tanker suffered minor injuries in the crash.
