Underwood Creek Rehabilitation and Flood Management, Menomonee River Watercourse, Milwaukee, Wisconsin

Abstract

Underwood Creek is a major tributary of the Menomonee River, extending approximately eight miles from its confluence with the Menomonee River, near Milwaukee County Grounds (MCG), to its headwaters in Waukesha County. The Underwood Creek Watershed is approximately 84 percent developed with a variety of urban land uses. Given this high degree of urbanization and the need to address local flood management concerns, Underwood Creek underwent considerable alteration in the mid-1960's, including channel widening and realignment, and the installation of concrete lining along a significant portion of its length. These channel alterations have resulted in increased peak discharges and channel velocities during periods of intense rainfall that successfully reduced peak water surface elevations along Underwood Creek, but contributed to flooding conditions along portions of the Menomonee River located downstream. As a result, the Milwaukee Metropolitan Sewerage District (MMSD) has initiated the design and installation of an approximately 1.2 million cubic meter (900 acre-feet) floodwater storage facility on MCG property that will receive excess floodwaters from Underwood Creek. Reduced peak discharges on Underwood Creek provide an opportunity to rehabilitate about 2 kilometers (6,600 feet) of this watercourse through removal of the concrete channel lining, and the development of a meandering bioengineered channel, with riffle and pool sequences. The adjacent floodplain will also be lowered and vegetated to promote the development of wetland areas and riparian habitat. The Underwood Creek Rehabilitation and Flood Management Project is a unique opportunity for MMSD to achieve multiple benefits from the rehabilitated channel and floodplain that include desirable aesthetic, habitat and public safety improvements, while providing appropriate management of the one percent probability (100-year) flood event. Preliminary engineering has been completed. Construction is currently scheduled for 2008 through 2010.