Behind a tangle of willows, every second of every day for almost half a century, recycled sewage has gushed into an El Monte creek and nourished one of Los Angeles County's most precious resources: the drinking water stored beneath the San Gabriel Valley.
Cleansed so thoroughly that it is considered pure enough to drink, this flow from the Whittier Narrows reclamation plant meets all government standards. Yet county officials now report that they have found some potent -- and until recent months undetected -- ingredients in the treated waste: prescription drugs.
As new technology enables detection of infinitesimally smaller doses of chemicals in the environment, Southern California water-quality officials have learned that an array of hardy pharmaceuticals are defying even the most sophisticated sewage treatments in use.
Around the world, waterways and groundwater basins are virtual drugstores, awash in low doses of hundreds of prescription drugs excreted by people and flushed down drains.
Wherever there is sewage, there are traces of whatever pills people have popped: antibiotics and antipsychotics, birth-control hormones and beta blockers, Viagra and Valium.
"There is no place on Earth exempted from having pharmaceuticals and steroids in its wastewater," said Shane Snyder, head toxicologist at Las Vegas' water provider, the Southern Nevada Water Authority, and one of the nation's leading experts on pharmaceuticals in water. "This is clearly an issue that is global, and we're going to see more and more of these chemicals in the environment; no doubt about it."
Locally, small amounts of medicines for depression, seizures, high cholesterol, anxiety, infections, inflammation and pain -- among other ailments -- have been detected in the wastewater that flows into California streams and seeps into drinking-water aquifers. The contamination raises questions about the safety of reclaimed water consumed by the public and the health of wild creatures that inhabit waterways.
The concentrations are so minuscule -- in parts per trillion, or a few drops in an Olympic-sized swimming pool -- that scientists suspect there is little or no human danger. They acknowledge, however, that no one knows the effects of ingesting tiny doses of multiple drugs continuously over a lifetime.
So far, concerns have focused mostly on the ecological threat. Biologists studying frogs on Prozac, insects dosed with anti-seizure drugs, algae killed by antibiotics and fish feminized by birth-control pills have discovered that some streams contain pharmaceuticals and synthetic estrogen at levels harmful to aquatic life.
"All the data we have compiled indicates these concentrations are trivial to public health. Even putting massive safety factors on this, it still wouldn't have a [human] impact," Snyder said. "Now for wastewater -- that's a different story. When you have a fish or endangered species that is exposed 24 hours a day, we do need to look at this."
With thousands of varieties of prescription and over-the-counter drugs being sold, there are no government standards restricting any of them in drinking water or in effluent released into streams or lakes.
Water and sewage agencies aren't even required to look for them -- and most don't. Testing of drinking water for drugs has been so infrequent that no one knows how much people are ingesting. A national association of wastewater agencies warned in November that pharmaceuticals are a "potential sleeping giant."
Los Angeles and Orange counties are among the world's leaders in recycling sewage to replenish water supplies, and officials there worry that the public's perception of the water supply will be tainted.
The Whittier Narrows plant, which has operated in El Monte since 1962, was the nation's first reclamation plant. Since then, nearly half a trillion gallons of treated sewage from Whittier Narrows and two other county plants have replenished the Central Basin aquifer beneath the San Gabriel Valley, which supplies water to 4 million people.
Sewage in Southern California undergoes some of the world's most rigorous cleansing -- tertiary treatment -- to protect rivers and streams from bacteria and nitrogen. Much of the wastewater then is routed into aquifers, where it remains for at least six months so soil can filter out more contaminants before potable water is pumped.
In November, the Los Angeles County Sanitation Districts reported at a scientific conference that they found high levels of ibuprofen, naproxen and acetaminophen in raw sewage coming into its Whittier Narrows plant, and very small concentrations going out.