Their conclusion: This stuff is not naturally part of the Gulf of Mexico water column, but it is nowhere near as bad as you thought it was:
The report concludes that decreased oil droplet size in deep waters is consistent with chemically-dispersed oil. The report also shows that dissolved oxygen levels remained above immediate levels of concern, although there is a need to monitor dissolved oxygen levels over time.
The report also confirms the existence of a previously discovered cloud of diffuse oil at depths of 3,300 to 4,600 feet near the wellhead. Preliminary findings indicate that total petroleum hydrocarbon (TPH) concentrations at these depths are in concentrations of about 1-2 parts per million (ppm). Between that depth and the surface mix layer, which is defined as 450 feet below the surface, concentrations fell to levels that were not readily discernable from background levels. The tests detection limit is about 0.8 ppm. Analysis also shows that this cloud is most concentrated near the source of the leak and decreases with distance from the wellhead. Beyond six miles from the wellhead, concentrations of this cloud drop to levels that are not detectable.
You can read the entire report here, and a synopsis of it is here. The entire report is a 4MB PDF document with enough scientific data and jargon to keep even the most radical lefty environmentalist busy for hours.
But, the report also blasts the loony rightwing conspiracy theories out of the water, too. Corexit, the primary dispersant being used, isn't "killing the Gulf," which the black helicopter crowds had claimed was part of Obama's masterfully sinister plan to depopulate the Gulf Coast, or something.
In fact, the stuff is doing exactly what it was chemically engineered to do: Disperse spilled oil into tiny droplets so that they mix more easily with the water and make the oil more readily available to oil-eating microbes that make it go away. And, the smaller droplet size means there are fewer surges in the biological activity that removes dissolved Oxygen.
Sadly, neither the wacko left nor the wacko right are much inclined to even read a government report, much less a peer-reviewed one. And even if they were able to sit still long enough to read it, they might find some subliminal message by reading it backwards under a full moon.
Skyclad, of course.
Gimme some feedback in the comments.