Effluent alters sexuality of fish.

Treated wastewater is altering the genes of native fish — making male fish more like females and females more like males.

A study is finding that an endangered fish species experiences dramatic hormonal changes after being immersed for three months in treated effluent from Pima County's Roger Road sewage plant.

For some hormones, male and female bonytail chub tested in wastewater contain up to five times more hormones of the opposite than of their own sex.
The University of and federal researchers worry it's not just fish that could be affected.

Sometime around 2020, Tucsonans may start drinking wastewater — in a much more highly treated form than the Roger Road plant now dumps into the Santa Cruz River.
Nobody knows if the compounds in treated wastewater can harm human reproduction because their effects on people haven't been thoroughly studied, said David Walker, a UA research scientist who is a lead investigator on the fish study, and Gail Cordy, a U.S. Geological Survey hydrologist who also works on it.

But Tucson Water will not serve treated wastewater "unless we could be assured that we were removing any elements that might be of concern," said its spokesman, Mitch Basefsky.
Researchers say the fish hormones are probably affected by what many scientists call endocrine disruptors.