Instead, they found high caffeine levels near Carl Washburne State Park and Cape Lookout, two areas not near the potential pollution sources, and low levels of caffeine near large population centers such as Astoria, Warrenton and Coos Bay.

CNN: Researchers find caffeine in waters off Oregon

Alternatively, it might be that people with low moods chose not to drink coffee because it contained caffeine, point out the researchers.

BBC: Coffee may prevent depression, scientists say