About the Oil Slick and Landfall Locations

The “estimated extent” of the oil slick is an estimate by the National Oceanic and Atmospheric Administration of where oil is mostly likely to go based on wind and ocean current forecasts, as well as analysis of aerial photography and satellite imagery.

The “surveyed extent” shows areas where oil was visible on the water surface during aerial and satellite surveys of the Gulf. The surveyed extents are not available every day and may be incomplete on occasion because poor weather conditions prevented observation in some areas.

The extents may vary widely from day to day because of changes in wind patterns and ocean currents. The loop currents are from NOAA and from Roffer’s Ocean Fishing Forecasting Service.

The locations where oil has made landfall are based on reports from federal, state and local officials. They are placed on the map on the day of the earliest report, and may change as better reports become available.