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Milwaukee Water has no blue-green algae problem

Aug. 7, 2014

Milwaukee water is free and clear of the cyanotoxin microcystin. Water quality testing results received Aug. 7, 2014 found there were no detections of microcystin toxins in any of the samples collected Aug. 5 from the Lake Michigan source water and the finished water from both of our water treatment plants.

Milwaukee has no history of toxic algae blooms that affected drinking water quality.

On Aug. 4, the City of Toledo, Ohio, lifted a three-day "do not drink" advisory, after finished water no longer tested positive for the cyanotoxin microcystin. Cyanobacteria, also known as blue-green algae, have the potential to grow in many surface water sources. In drinking water, they are most commonly known for causing taste and odor problems. In some cases they can also release cyanotoxins, which raise health concerns related to the liver, nervous system and gastrointestinal system.

The Milwaukee Water Works is fortunate to have a relatively clean source of water in Lake Michigan and in the water treatment process, we use ozone disinfection, which destroys harmful microorganisms and contaminants. The use of ozone disinfection is recognized by the Water Research Foundation as an effective treatment to destroy microcystins.

To better understand the risk of Lake Michigan having an algae bloom like Toledo experienced, we consulted with Dr. Carmen Aguilar from the University of Wisconsin-Milwaukee School of Freshwater Science. Dr. Aguilar said there is no problem in Lake Michigan with the blue-green algae which produces the toxin. She said the morphologies of Lakes Erie and Michigan are very different. Lake Erie is shallow, warm and eutrophic (contains high levels of nutrients) while Lake Michigan is narrow, deep, and oligotrophic (contains very low levels of nutrients). Dr. Aguilar said there is a bit of eutrophication in some near-shore areas of Lake Michigan. But she said that since the Milwaukee Water Works intakes are very far out into the lake and in deep water there should be no impact from this near-shore eutrophication. Water for the Linnwood Plant is drawn from an intake 6,565 feet from shore at a point where Lake Michigan is 62 feet deep. The Howard Avenue Water Treatment Plant intake is 11,767 feet from shore where lake water depth is 57 feet deep.

Currently, there are no federal regulatory guidelines for cyanobacteria or their toxins in drinking water. They are listed as candidates for possible national monitoring under the UCMR-4 program to begin in 2018. The "do not drink" incident in Toledo is a reminder that the protection of our source waters is critical to the protection of public health. It also demonstrates how water providers act with an abundance of caution when there is the possibility of health concerns resulting from tap water.