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patterns and rainfall intensities, and river flows and levels all influence whether an overflow occurs, there is an increasing probability of overflows anytime the flows in the system go above the 175 MGD level. Finally, as base flow and infiltration/inflow from newlydeveloping areas in the coming years are added to the system, the instances of overflows would increase unless abated in accordance with the Wet Weather Flow Management Plan that was adopted by the MWMC and the Cities in 2001. An indicator of this trend seems to have occurred in December of 2003 when the sanitary system experienced a bypass event under conditions less than the one-in-five year storm event. Attached as further information are two tables which present the historical exceedances of both Dry Season and Wet Season maximum month flows (existing rated capacity) to the regional treatment facilities. In order to meet the State standard, equivalent to no more than one overflow in five years, the peak flow capacity of the treatment facilities willhave to be increased from the current level of 174 MGD to 277 MGD before the year 2025. DEQ requires adequate treatment capacity by the year 2010 to prevent system overflows from winter storms. The Facilities Plan outlines the capital improvement projects, derived from an extensive analysis of options andphasing considerations, which are necessary to provide the higher peak flow capabilities. Attachment 1: Dry Season Maximum Month Flow Fact Sheet Attachment 2: Wet Season Maximum Month Flow Fact Sheet c: Susie Smith, MWMC General Manager L:\CMO~004 Council AgendasWI040628\S0406287-attD.doc