Today as Brett and I were driving back home from Washington we caught a glimpse of the Shenandoah River from I-66 that was somewhat unusual. We took the next exit and drove around on back roads for awhile looking for a path to the river so we could take some pictures.
What we saw was a small muddy tributary flowing into the relatively clear Shenandoah. When one stream flows into another, the two bodies of water don’t immediately mix together thoroughly because of slightly different densities (this is how distinct water masses in the ocean can be traced over long distances). If one of the water bodies has a very heavy sediment load the sediment plume makes the effect easily visible, as in this striking example:
This particular sediment plume is also visible in Google Earth images (if you want to find it yourself, the coordinates are latitude 38.956983 N, longitude 78.182973 W).