Kinnickinnic River Rehabilitation

The Kinnickinnic River (KKR) watershed is an approximately 25-square-mile, urban drainage area located on the south side of the City of Milwaukee, Wisconsin. In past decades, the KKR channel was widened, realigned and lined with concrete, all in an effort to provide flood management and reduce peak water surface elevations.

However, continued development in the watershed and increasingly frequent, high-intensity rainfalls resulted in higher water surface elevations and an expanded 100-year floodplain. South side Milwaukee area residents and other local stakeholders considered the KKR a dangerous urban eyesore that had caused multiple drownings. In the recent past, American Rivers, a national non-profit environmental organization, identified the KKR as the seventh most endangered river in the United States.

Given these conditions, the Milwaukee Metropolitan Sewerage District (MMSD) initiated a series of projects with goals that included improving flood management and public safety, providing channel and bank stability, installing native vegetation to restore wildlife habitat, enhancing fisheries and stream biota, facilitating public use and enhancing sustainability.

MMSD selected SEH to complete a watercourse rehabilitation project that addressed many of these goals and set the stage for future upstream improvements. SEH’s rehabilitation design included removing approximately 500 feet of concrete-lined channel and rehabilitating approximately 1,000 feet of watercourse. The project includes a stone-lined channel featuring riffles and pools, stabilizing steep embankments in the narrow urban corridor, constructing approximately 2,600 feet of tiered retaining walls and developing a multi-use recreational trail and maintenance path.

The award-winning KKR rehabilitation project has been hailed by the MMSD, local residents, stakeholders and professional organizations as being highly successful and a great example of the multiple benefits of urban river rehabilitation projects.

Upstream Before - Looking upstream, toward the South 6th Street Bridge, along the Kinnickinnic River at the downstream end of the concrete-lined channel. Note the 84-inch diameter storm sewer pipe located on the left, which created an unsafe 10-foot-deep plunge pool at the end of the concrete channel.
Upstream After - Looking upstream at the replacement Kinnickinnic River South 6th Street Bridge, with maintenance trail and future bike path on the left, a re-graded north embankment slope, a rehabilitated stone-lined channel and tiered perimeter wet-cast concrete block retaining walls.
Downstream Before - Looking downstream from the Kinnickinnic River South 6th Street Bridge at a 500-foot-long, 60-foot-wide, concrete-lined channel, confined by a MMSD Combined Sewer Overflow (CSO) control facility and outfall on the right and a steep, approximately 50-foot-tall concrete embankment on the left.
Downstream After - Looking at the downstream rehabilitated Kinnickinnic River segment that transitions from tiered retaining walls into a more appealing watercourse that includes a meandering stone-lined channel, a hydrated floodplain that is inundated with stormwater runoff approximately 16 times per year and variable embankment slopes planted with native vegetation.

 

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