Oil spill workers raced against time in the Gulf of Mexico, hoping to seize on at least one more day of calm in their fight to contain a huge and growing slick before winds turn against them.

Cleanup crews along the U.S. shore have had a few days’ reprieve as the slow-moving slick, from oil spewing from a damaged deep-water well, remained parked in waters that for now are placid.

“The winds are helpful to us, but on Thursday they begin to be less helpful,” Louisiana Governor Bobby Jindal said in New Orleans.