Which are more harmful oil or grass clippings?

If you were to pour a quart of oil and a bag of grass clipping down the storm drain at the same time clearly the oil would be the most harmful to storm water.

However, most people know not to pour oil down the storm drain but don't think twice about hosing their yard waste down the storm drain.

And when you examine the overall cumulative effect of thousands of people sending their grass clippings down the storm drain versus the few who put oil down the drain it becomes one of the top pollutants of storm water.

Watch the 2005 Public Service Announcement (1.3mb wmv)

Watch the 2004 Public Service Announcement (575k wmv)