95-Mile-Long Slick in the Gulf of Mexico?

This report on SkyTruth’s handy pollution Alerts system caught my eye yesterday afternoon:

SUSPECTED SLICK IS SEEN AS LONG NARROW PLUME APPROXIMATELY 95 MILES LONG AND 1 MILE OR LESS WIDE.

That sounds like bilge-dumping from a passing vessel — an activity that is illegal in US waters (and much of the rest of the world).   Intrepid SkyTruth intern Patrick busted somebody for bilge-dumping off Angola last year using satellite radar imagery and AIS data.  The report was submitted to the Coast Guard-operated National Response Center by image analysts at NOAA.  We’re thrilled that they’ve started reporting their analyses of possible pollution incidents to the NRC, so we can easily incorporate them into our Alerts system.  (We like to think our Gulf Monitoring Consortium activity helped spur NOAA to get their experts into the game in a more public way.)

NOAA’s analysts now think it’s probably not oil; more likely it’s natural surfactant caught in the convergence zone between two water masses.  I agree; this is close to the edge of a loop current now in the northeastern part of the Gulf.  And bilge-dump slicks usually look a lot sharper than this (see a slideshow of our examples from radar imagery).

Here’s detail from a MODIS/Terra satellite image taken at 16:50 UTC on April 14, 2013, showing the apparent slick.

Location map showing detail from MODIS/Terra satellite image taken on April 14, 2013.
Detail from MODIS/Terra satellite image of slick (dark, east-west trending streak) probably caused by natural surfactants accumulating along the convergence zone between ocean currents.