 |
| Foam on Bull Creek |
When we first started hanging out on Bull Creek, I was concerned about the collection of foam I would find in eddies beside rapids. This eight mile section of the stream is designated as one of only a few
Outstanding Water Resource areas in Missouri. Calling the MDC, I learned that foam can be a normal finding on the cleanest of streams.
 |
| Foam on the shoreline of a lake, created by wave action - Photo from The Waterline |
David Casaletto just sent me a link to
his story from on foam from
Ozark Water Watch describing the scientific basis of foam creation on water.
"On lakes, in bathtubs and in mugs of beer, the cause for foam is the
same. Agitation at the surface causes air to get under the surface film
of the water. Weakened surface tension is unable to force the air out,
but rather keeps water wrapped around a volume of air, creating a
bubble. If this happens for long enough, foam is created. On lakes, the
agitation is usually due to wind, and the resulting foam will collect on
the downwind side of the lake. In streams you will see the foam in
eddies or floating downstream, and it is created by the flow of the
water disturbing the surface film."
The quote above is from the Waterline which goes on to describe in detail how foam is formed. It describes the relationship of surface tension, aeration, and particles in the water to foam formation. Not all foam is benign as organic compounds from decomposing plant or animal matter and other pollutants can make foam appear more commonly. Rather than attempt an explanation,
go to the Waterline story for details.
Ozark Waters is a valuable newsletter which you can subscribe to electronically for free at this website.
