The oil slick from the massive spill in the Gulf of Mexico has reached the mouth of the Mississippi River and is moving toward delicate ecosystems for birds and marine life. Booms were set in place to prevent oil from reaching grasslands and sandy beaches, but have become ineffective with 5-foot swells pushing oily water over the boundaries. The spill is five times larger than first estimated and is threatening to become America’s worst environmental disaster in decades. Hundreds of species of fish, birds, and other wildlife living on the Gulf Coast will be threatened as the oil reaches shore. After the BP oil rig exploded and sank last week, around 5,000 barrels, or 200,000 gallons, began pouring out each day. It may take up to three months to plug the well.