There was a high-pressure system over B.C.'s South Coast on April 8th, producing blue skies and very light breezes on English Bay. It was, one might say, perfect weather for an oil spill.

Marine accidents typically happen when conditions are foul. There is fog, or driving rain, or high winds. But on the day the Marathassa accidentally discharged 16 barrels of bunker fuel, while resting at anchor midway between Jericho Beach and Stanley Park, conditions were ideal for a cleanup.

Which is why the Coast Guard's slow response to that spill is so troubling.

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The Coast Guard has praised itself for getting to the spill about 90 minutes after it was first reported by a recreational boater, and for having the Western Canada Marine Response Corp. on scene in a little more than four hours. But the Marathassa wasn't contained by a boom until 12 hours and 39 minutes had passed. And by then, the oil in the water had spread so far that it would take more than a week to clean Vancouver's beaches.

If it's that hard to contain and clean up oil spilled on a calm day, just a 15-minute boat ride from the main harbour, how difficult would it be to respond to a spill on a remote section of the coast, in bad weather?

That's a question a lot of British Columbians should be asking themselves these days as they contemplate the possibility that two major oil pipelines could be built to the West Coast. Enbridge's proposed Northern Gateway pipeline would bring 525,000 barrels oil sands bitumen daily to Kitimat, where it would be shipped by tanker through the twisting channels of the Central Coast. Kinder Morgan's Trans Mountain pipeline expansion project would nearly triple to 980,000 bpd the amount of crude being delivered to Vancouver, for shipment past the Gulf Islands and around Victoria.

After the Marathassa spill, the Coast Guard described the cleanup effort as "exceptional" and proof that it meets high oil-spill response standards.

According to the regulations Canada has adopted, responders should be able to be on scene, ready to deal with a 1,000-barrel spill in six hours in the harbour. But for a 67,000-barrel spill, within 50 nautical miles of Vancouver, the crews have 72 hours to deploy.

So if you thought the containment of the Marathassa was slow, imagine waiting another 60 hours for crews to get booms around a ship leaking in Georgia Strait. By then, oil would be all over the beaches on the Gulf Islands and slopping up on the shorelines around Victoria.

But 72 hours is not the worst-case scenario for response times.

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When the B.C. Ministry of Environment did a West Coast oil-spill-response study in 2013, anticipating a possible increase in tanker traffic because of the Northern Gateway proposal, the report cautioned that a response simply wouldn't be possible in some locations at some times.

"Even when wind and waves are moderate enough that on-water containment and recovery equipment can be deployed, other conditions may preclude a response," the report warns.

According to the study, "a mechanical spill response" would be impossible because of environmental conditions 45 per cent of the time off the north coast of Haida Gwaii, 51 per cent of the time at South Moresby and 50 per cent of the time in Hecate Strait, between Vancouver Island and Haida Gwaii.

Anyone who has sailed B.C.'s wild coast will tell you that when the winter gales set in, the wind can blow for weeks at a time. Rain slashes down. Fog banks grow so thick you can't see the shore 100 metres from the rocks.

In those conditions, response crews will huddle in safe harbours, waiting for the weather to break, and not one drop of oil will get cleaned up for days. So if you think the Marathassa response was slow, next time it could be much, much worse.