The Charter Townships of East China and China, Michigan, built a state-of-the-art 2.7 MGD membrane microfiltration water treatment plant, the first to use the Zenon system in the Midwest, to address long-standing problems with their source water and to meet current and proposed regulations. The plant has been on line since July of 2001. This paper discusses the performance of immersed membrane microfiltration performance using Great Lakes water, which is a very difficult water to treat because of its extreme cold temperature (0.5 ºC). The paper covers five years of performance and will be useful for utilities considering membrane microfiltration for their capital improvement, plant operators, and for drinking water design engineers. The WTP is a three train system that utilizes ZeeWeed® 500 membranes. Each train consists of fifteen cassettes with eight hollow fiber membrane modules. Raw water is pumped into the membrane tanks via raw water pumps. After membrane filtration the treated water is pumped to ground storage before being lifted to two elevated tanks. A 1mm traveler screen is installed to protect the membranes. However, due to the mechanism of these traveler screens, some carry over of coarse materials got into the downstream. These materials created a permanent damage to the membrane fibers, requiring that the membranes be replaced. For additional protection a 500um cartridge filter (basket filter) were installed downstream of the traveler screen and upstream of the membrane systems. Thus, new membrane replacement were installed in March 2004. The membrane system performance over a period of five years is presented in details with focus on permeate quality, particle counts, permeability of the membranes, flux, transmembrane pressure (TMP), membrane integrity test (MIT), and recovery clean analysis for each of the three trains. O&M cost is also presented. Includes tables, figures.