Blissed-Out Fish on Prozac

Jeffrey Hawkins Writer likes to say that the average drop of water entering the Mississippi River headwaters north of Minnesota will be used 11 times before it reaches the Gulf of Mexico. That drop might irrigate crops, flow through wastewater treatment plants, pour out of residential taps, move through digestive systems, arc into toilet bowls, swirl down into sewers, and then do it over again. Whatever its fate along its 2,300-mile journey South, this water will mix with all kind of chemicals, human metabolites, and unnatural compounds. Writer can attest to that. When he floated down the big river in the early 1990s on a government research boat measuring contaminants, he detected everything from heavy metals to pesticides to caffeine.

But the waters of Colorado, Writer’s current base of employment, should be an entirely different matter. On a late September morning, Writer and I are driving along the outskirts of Boulder. The road is lined with picturesque stands of cottonwoods and willows; sheep graze lazily in sun-dappled fields. The seasoned environmental engineer points to craggy, snow-capped mountain peaks looming over the hills above us, a source of virgin water feeding into the Boulder Reservoir, the town’s primary source of drinking water, and eventually its main tributary, Boulder Creek.

We are on our way to the heart of town, where Writer, a hydrologist at the United States Geological Survey (USGS), wants to show me a favorite local haunt near the University of Colorado, Boulder. It’s a bucolic spot on Boulder Creek where families swim, dogs frolic, and children go tubing in the summer. Upstream of Boulder’s central wastewater facilities, the crystal clear water is fed mainly by the runoff from the Arapaho Glacier and scores of streams like it, migrating down from the Rockies through waterways notched into the hills.

So when