A USGS scientist collecting a water-quality sample from Boulder Creek, Colorado. USGS scientists have shown that many chemicals discharged from municipal wastewater treatment facilities persist for miles downstream at levels known, or suspected, to cause adverse health impacts to aquatic organisms—including endocrine disruption in fish. Photo credit: Jennifer Beck, USGS.

Scientists setting up equipment used to apply artificial rainfall to a small test plot on a field that received an application of biosolids. The scientists captured the runoff from the plot for later chemical analysis. Photo credit: V. Cory Stephens, USGS.

This diagram of the nitrogen cycle shows were in the cycle antibiotics could impact the ability of denitrifying bacteria to process nitrates and nitrites in groundwater. The diagram is a modified version of figure 9 from USGS SIR 2004-5144, page 16.

A USGS scientist prepares a sample to test the effect of antibiotics on subsurface denitrifying bacteria within a glove box. A glove box allows scientists to work with samples in an anaerobic (no oxygen) atmosphere, the conditions under which denitrification occurs. Photo credit: Jennifer C. Underwood, USGS.

USGS scientist holding a stone from Boulder Creek, Colo., that's covered with a biofilm. USGS scientists found that the biofilm that coats many of the stones on the bottom of the creek absorbs endocrine-disrupting compounds. Photo credit: Ronald C. Antweiler, USGS.

Scientists used florescent dye and bromide to track river water to which two emerging contaminants had been added - 4-nonylphenol and 17β-estradiol. This allowed the scientists to study the natural attenuation of the two compounds as they were transported down the Redwood River, Minnesota. Photo credit: Jeffrey H. Writer, USGS.

The Boulder Wastewater Treatment Facility, Colorado (circa 2005), before the upgrade to an activated sludge treatment process. A team of scientists demonstrated that the upgrade to the treatment process at the wastewater treatment facility reduced the level of endocrine disruption in fish exposed to wastewater effluent discharged from the facility.

USGS scientists collecting a sample from South Fork Iowa River headwaters near Blairsburg, Iowa (Site ID 05451070) for analysis of phytoestrogens and some mycotoxins. The scientists collected 75 stream samples from across in Iowa during 2008. Photo Credit: M. Kate Holt (USGS).

Average concentrations of antidepressants in water, sediment, and fish neural tissue from Boulder Creek just below the point where wastewater from a sewage treatment plant is discharged (USGS Site ID 400305105103901). Since concentration units differed for each sample type, the concentrations were normalized to the highest single antidepressant concentration in each sample type (highest concentration was set to equal one). The graph shows that fish selectively absorb some antidepressants more than others.

USGS scientist dissecting a fish to determine possible effects from exposure to endocrine disrupting contaminants.

USGS scientist measuring pH and other water properties on the banks of Fourmile Creek, Iowa, before collecting a sediment sample for laboratory biodegradation experiments on detergent degradation products.

Scientist collected earthworms from a soybean field fertilized with biosolids. The earthworms were analyzed for 77 different chemicals; 20 chemicals were detected in the earthworms.