UPDATE: A friend had the wise idea to query the ranger on duty at Nisqually. I am fortunate to know people as curious as I am !
The ranger shared that “the water often is orange-red because of bacteria in the water attempting to “feed” on the iron components in it. This kind of bacteria tends to oxidize the iron creating an orange-color, but water also helps to stop the oxidizing process”
He also shared this website as a good resource for this and other questions. https://www.fairfaxcounty.gov/publicworks/stormwater/whats-stuff-stream.
What’s that Stuff in the Stream? | Public Works and Environmental Services – Fairfax County, Virginia 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. Natural foam appears as light tan or brown, but may be white and has an “earthy,” “fishy” or “fresh cut grass … www.fairfaxcounty.gov
This is a natural phenomenon, most common in late winter and spring. I’ll be looking at the refuge much more closely the next time I am there for a walk. Cheers to curiosity !
A couple photos from my walk yesterday at Nisqually. Does anyone know why the water in this stagnant pond turns orange every year ?