A study by the U.S. Geological Survey found that two different kinds of human-associated bacteria, as well as three kinds of human viruses were detected in Milwaukee streams within the Menomonee River watershed.
“Leaky infrastructure and overflows from sanitary sewers can contaminate urban waterways, and the detection of human-associated bacteria and viruses indicates the presence of sewage, a potential health hazard,” said Peter Lenaker, a USGS scientist and the lead author of the study.
From 2009 to 2011, scientists with the USGS, U.S. Department of Agriculture and University of Wisconsin-Milwaukee sampled surface water from six Menomonee River stream locations in Milwaukee for human sewage contamination.
They tested 228 samples for eight types of human viruses and two types of bacteria associated with human waste.
They found human viruses were present in up to 38 percent of the samples. Human bacteria was even more present.
Scientists detected adenovirus C, D, F, A and enterovirus.
Adenovirus C, D, F were the most common of all the viruses. They cause minor respiratory illnesses.
Adenovirus A and enterovirus cause symptoms similar to the common cold.
At least one of these viruses was found in 20-73 percent of samples during low water flows and 24-61 percent during high-flow events depending on sampling location.
Little Menomonee River near Freistadt in Mequon, Wis., Menomonee River at Wauwatosa and Menomonee River at 16th St. in Milwaukee had the highest total virus concentration/occurrence.
The bacteria associated with human waste were human Bactroides and Lachnospiraceae. These bacteria were found in 43-94 percent of samples during low-flow periods and 67-100 percent during high flows. Sites with highest concentration of bacteria were Honey Creek and Menomonee River in Wauwatosa and the Menomonee River at 16th St. in Milwaukee.
These bacteria do not pose health hazards and are common in the human body. They enter waterways through sewage.