Public Works and Environmental Services

CONTACT INFORMATION: Our administrative offices are open 8 a.m. – 4:30 p.m., Mon - Fri
703-324-5500 TTY 711
12000 Government Center Parkway
Suite 449, Fairfax, Va 22035
Shannon Curtis
Chief, Watershed Assessment Branch

What's that Stuff in the Stream?

Streams in Fairfax County support many different types of life. Fish, insects and salamanders live in many streams. Sometimes we may see things in streams that we do not recognize.

How to Tell the Difference Between Natural and Man-Made Foam

Natural sources from decomposition of leaves, twigs or other organic substances:

  • Natural foam appears as light tan or brown, but may be white and has an “earthy,” “fishy” or “fresh cut grass” odor.
  • Natural foam occurs at many locations along a stream, accumulating on or near the bank, or on other material in the stream.
  • Natural foam can be seen in eddies or floating downstream.
  • Natural foam increases after rain storms as rainfall transports the decomposed plants to the stream.
  • Natural foam can cover large areas and can accumulate in large amounts. 

Man-made sources include yard fertilizing, car washing, washing machine discharge, sanitary sewer or septic field failures:

  • Foam from man-made sources is usually white and fragrant or perfumed.
  • Foam from man-made sources will accumulate near the source of the discharge.
  • Foam from most detergents is biodegradable and will disappear quickly.
  • Foam from leaking sanitary sewer lines or septic fields will have a foul odor.
  • Foam from man-made sources is likely not related to rain storms.

If you see foam, suds or bubbles in a Fairfax County stream that you suspect is a result of a sanitary sewer line break, or if you detect the odor of sewer gas, call the Fairfax County Wastewater Collection Division at 703-323-1211, TTY 711.

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