20 years ago Cryptosporidium passed through a Milwaukee water treatment plant. The microorganism caused an estimated 400,000 cases of gastrointestinal illness and at least 69 deaths. It was the largest waterborne desease outbreak recorded in U.S. history.
Since the outbreak, the city’s water utility, which draws its supply from Lake Michigan, has invested $417 million in improvements to infrastructure, monitoring and treatment.
Beginning in 2004, Milwaukee Water Works launched an aggressive program to monitor for emerging contaminants including estrogen and testosterone, flame retardants, pesticides, explosives and pharmaceuticals. Milwaukee Water Works tests for more than 500 chemicals annually, and posts its monitoring results online. The majority of water systems in the US focus only on a standard list of 91 contaminants regulated by the U.S. Environmental Protection Agency.
Since the Cryptosporidium outbreak of 1993, Milwaukee has made numerous improvements to its drinking water treatment. An $11 million project extended the Howard Avenue water intake 4,200 feet to a distance of two miles off Lake Michigan’s shoreline, beyond the path of contamination from the city’s industrial harbor. The water enters a nine-step treatment process that includes ozone disinfection, sedimentation and filtration.
At the other end of the city’s water system, the Milwaukee Metropolitan Sewerage District tested a state-of-the-art sewage filtration system. The goal was to catch emerging contaminants resistant to removal by conventional wastewater treatment along with phosphorus, a nutrient that contributes to algae blooms and fish kills.
As a result of the improvements, Milwaukee has become a leading municipality with respect to drinking water treatment.