Whitewater State Park, located in Winona County, is known for its scenic limestone bluffs, deep ravines, and spring-fed Whitewater River. The middle branch of the Whitewater River flows through the park and is spanned by several highway, road, and foot bridges. An extreme storm in 2007 severely damaged the river channel downstream of the Highway 74 bridge. In 2016, the DNR undertook a comprehensive channel restoration using natural channel design principles, seeking to realign the river to emulate an existing stable reference reach upstream of the project area.
Working closely with the DNR, Barr developed a design recommendation report, final design drawings, technical specifications, and cost estimate to reconfigure a 1,700-foot channel reach. Hydraulic modeling was conducted using both one- and two-dimensional models to evaluate fish passage, stabilization measures, and upstream project impacts. Barr used natural channel design, fluvial geomorphology, and general engineering principles to develop the primary design elements, including reconfiguring the upstream segment of the project reach, constructing elliptical rock riffles, reconstructing a damaged boulder weir downstream of the highway bridge, installing boulder clusters to provide habitat, and lowering an overbank area to provide floodplain connectivity. Riverbanks were stabilized using toe wood and native vegetation that can thrive in the site’s difficult growing conditions. The design, developed in close collaboration with the Minnesota Pollution Control Agency, included detailed erosion-control sequencing.
Construction is being carefully timed to respect trout spawning periods when in-channel work is restricted, while not leaving the channel in a vulnerable condition for extended periods of time.