More than two months after oil from BP's exploded well on the seabed first reached shore in Louisiana, tar balls have washed on to two Texas beaches, meaning that all five states on the Gulf of Mexico have now been affected. Bad weather has forced a fleet of skimmers that should be cleaning the worst-hit areas to stay in port. For more than a week, storms have made the water off Florida, Alabama and Mississippi too choppy for the boats to operate. BP was operating the Deepwater Horizon drilling rig when it exploded on 20 April, killing 11 workers and starting the worst oil spill in the Gulf's history.