Nick Fetty | October 7, 2014
A report released by the United States Geological Survey last month suggests that pharmaceuticals and other potentially hazardous substances from treated wastewater can contaminate shallow groundwater after being released into streams and other waterways.
The research was conducted on Fourmile Creek and Watershed near Des Moines in 2012. In October of 2012 wastewater accounted for 99 percent of the creek’s flow and this number dropped to 71 percent in December 2012. During these months, the creek experienced persistent dry conditions which is when contaminates are most likely to seep into groundwater.
The study tested for 110 different pharmaceutical compounds in addition to hormones and chemicals from personal care products. The researchers concluded that between 48 and 61 pharmaceuticals were present in the water tested downstream from the wastewater discharge point. Concentrations were as high as 7,810 parts-per-trillion for metformin, a chemical used in antidiabetic medication.
This contamination was also taking place in groundwater up to 65 feet away from the banks of Fourmile Creek. Between 7 and 18 pharmaceutical compounds were detected in these groundwaters with concentrations of fexofenadine – an antihestemine – as high as 87 parts-per-trillion.
This study was part of USGS Toxic Substances Hydrology Program.
The Fourmile Creek Watershed covers 120 miles mostly in northern Polk County but also areas of Boone and Story Counties. Approximately 64 percent of the land in the watershed is used for agriculture while the remaining 36 percent is urban. In 1877, a train carrying members of the P.T. Barnum circus and other passengers crashed while crossing over Fourmile Creek, killing 20 and injuring 35 more.