I live in River Ridge - this is absolute bullshit.
Runoff from a parking lot where cars leak oil and the rainbow diffraction of the oil residue floating on a drain grate is bogus.
Go out on your driveway where your car has dripped oil drops while it was parked there, and run a hose for a bit,
you will have the same thing - the oil floats as a film and diffracts light into a rainbow, just like a soap bubble does.
Now there is one thing going on here that is obvious when you look in from the distance, and that is the pollution
in the air from the burning off of the boomed oil into burn puddles - the sky has a yellowish brown tinge
in the air, just like it used to look like in Los Angeles in the 60's ans 70's. Air pollution.
The smoke plumes drift into the air and the wind currents from the Gulf carry it over the land.
Yes, it rains down on the ground and is carried to the drains, but it is hydrocarbon oxides,
like the acid rain that Saint Louis used to experience when coal was burned there, but not nearly as concentrated.
the 'Oil' doesn't rain down, the water disolves the CO2 or SO2 and creates some acidic compound like
carbonic or sulpherous acid to kill plants or disolve limestone - just like it always does.
http://en.wikipedia.org/wiki/Carbonic_acid
http://www.ucc.ie/academic/chem/dolchem/html/comp/h2so3.html