Milwaukee receives its water from Lake Michigan. The origin of the contamination was found to be sewage that passed through the plant’s filtration system. Where the sewage came from is still unknown but it might have been run off from a farm or feed lot.
In March 2001, the solids contact unit in the surface water treatment plant was emptied and all the sludge removed from the bottom in order to inspect, clean and repair a crack that had formed in the cement floor. This type of repair should normally be done in February, so that the spring breakup and runoff will not affect the system.