Edit: Following pesfandiar's link about caffeine pollution in the Pacific Northwest, I found this about Puget Sound:[0]
> Of all the flavors trickling downstream, artificial vanilla dominates the sound, Keil said. For instance, the team found an average of about six milligrams of artificial vanilla per liter of water sampled.
Yes, 6 mg/L in water! That's not trace contamination. But "Puget Sound is vanilla flavored!" isn't so scarey, I guess.
0) https://news.nationalgeographic.com/news/2009/11/091112-drin...