Natural and unnatural foam: got it. How can I tell what kind of foam it is?

Although it's difficult to know for sure, foam from various sources can have different characteristics.

Natural foam usually:

  • appears as light tan or brown in color, but may be white;
  • smells earthy, fishy or has fresh cut grass odor;
  • can occur over large areas and accumulate in large amounts, especially on windward shores, in coves and eddies; and
  • dissipates fairly quickly, except when agitated (as in high wind conditions).

Unnatural foam from human activity usually:

  • appears white in color;
  • gives off a fragrant, perfumed or soapy odor; and

usually occurs over small area, localized near a source of discharge.

Show All Answers

1. Let me ask about the foam first. What causes foam to appear on lakes, rivers, and streams?
2. OK, good info. When am I most likely to see natural foam on a waterbody?
3. Well, that makes sense. But is foam harmful?
4. Natural and unnatural foam: got it. How can I tell what kind of foam it is?
5. What should I do if I suspect a waterbody's foam is the result of a chemical release or spill?
6. Wow… I’m learning a lot! Now that I know about foam, what causes surface scum on a lake?
7. But why does the water quality of our lake seem to get worse throughout the summer?