Cryptosporidium has not been detected in Milwaukee’s drinking water coming out of the Linnwood treatment plant on the Lake Michigan shore since 2002 or the Howard Ave. plant on the south side since 1999.
Cryptosporidium and Milwaukee made national news 18 years ago this month when the parasite caused the largest epidemic of documented waterborne disease in U.S. history. About 403,000 people in the metropolitan area were sickened with watery diarrhea, and the illness was responsible for at least 69 deaths.
The city spent $89 million from 1994 to 1998 to upgrade the two water filtration plants and prevent another outbreak. The city is continuing to invest several million dollars a year – nearly $180 million since 1998 – to maintain its water treatment and distribution systems, and ensure the water is safe to drink.
Installing better water monitoring equipment was the first priority after the outbreak. Turbidity meters show whether particles of all kinds – parasites or soil – remain suspended in treated water. Turbidity, or cloudiness, of filtered water is measured constantly inside both plants and results are reported every 5 seconds.
The first construction project was to extend the Howard Ave. plant’s water intake pipe an additional 4,200 feet out into Lake Michigan. The longer pipe moved the intake away from the plume of contamination flowing out of the Milwaukee harbor and south along the shoreline. New filters of anthracite coal atop crushed sand, and new filter drains, were installed at both plants.
More importantly ozone gas now is dispersed into lake water as the first step of the treatment process at both plants. Ozone is capable of destroying Cryptosporidia and other disease-causing microbes. Typical doses of chlorine are not capable of killing the parasite.