Like the 100th article looking into this

The 2004 study showed that certain chemicals from pharmaceuticals and personal-care products made it through the Boulder Wastewater Treatment Plant and into Boulder Creek. Ninety percent of the white suckers swimming downstream of the plant were female. Upstream, there was an even split.

"What we see in the fish downstream is as if they are taking birth control pills," Norris said.

The female fish - both the transsexuals and the original girls - had smaller-than-average ovaries. The remaining males produced less sperm, showing the water effluent also has contraceptive effects, he said.