The Army Corps of Engineers has just proposed a $6 million project to build a massive, unsightly concrete floodwall on the banks of the Des Plaines River behind West Avenue in Riverside, a larger levee along Groveland Avenue, a raised roadway just south of and parallel to Maplewood Road, and a floodgate across Forest Avenue.
These structures could increase flood levels for areas outside of the levee, including homes upstream which are not currently in the floodplain, and areas west of First Avenue including the high school and zoo.
This project would saddle local government and taxpayers with millions of dollars in expense (a minimum of 35 percent of the cost), and give scant protection to the homeowners the structures are intended to benefit. It reflects an antiquated approach to flood control, one that is being widely abandoned around the world as short-sighted and unworkable.
There is a better way. In Riverside, there are at least two options that would actually reduce flooding by giving the Des Plaines more room to flow. Two bridges — the railroad bridge just south of West Avenue, and the Forest Avenue bridge — currently impede the flow of the Des Plaines during floods, forcing water to back up. Modifications to those bridges could significantly improve the flood problems of residents.
A Government Accountability Office (GAO) study of recent Midwest floods points out how counterproductive levees can be:
“Available studies and the experts we spoke with agreed that levees generally contribute to higher flood levels above and within the levied part of a river … causing the water to back up, just as the loss of a traffic lane on a busy highway causes heavy traffic to become congested.”
A large empirical 2012 study of levees in Illinois and Iowa demonstrates the effect:
“[A]t all sites upstream of levees or within leveed reaches, [flood] stages increased [after the levees were built]. …The increases empirically documented here were quite large, ranging from a maximum increase of +42 cm on the Iowa River at Marengo, Iowa, up to 2.3m on the Wabash River at Mt. Carmel, Ill.”
This study also showed that the simple models that the Corps uses to model river dynamics routinely underestimate the actual increases in flood heights caused by levees.
It is tempting to rely on the expertise of federal authorities and assume they know best. But doing so is a mistake. According to the Association of State Floodplain Managers, most state and local governments “simply have assumed that the federal programs represent an acceptable standard of care. They perhaps do not realize that these very approaches can induce additional flooding and damage within their communities.”
Groveland Avenue and West Avenue are in the existing floodplain. Anyone who has ever played in the water can intuitively see that a raised roadbed along Park Place, designed to prevent water from flowing south across the land onto the floodplain, is likely to cause the water to back up to the north, toward homes that are not in the floodplain. The Corps itself acknowledges that even “small changes in flood stages can have significant impacts in the study area due to the flat topography.”
Raising flood levels also threatens our high school. The eastern side of Riverside-Brookfield High School is in the floodplain, directly west of the proposed levees. If the construction of these levees increases flood stages, the high school would be directly affected.
The perennial exposure of homes in the floodplain to flooding is a legitimate problem, and merits a solution. But shifting the flooding around is not a solution.
This letter was signed by Riverside residents Steve Daily, Lani Anderson, William Anderson, Tabby Cochran, Jack Cochran, Gail Crossman, Jeff Baron, Sheila Daily, Loriann Duffy, P.J. Duffy, Charles Klingsporn, Virginia Klingsporn, Audrey Korslund, Doug Korslund, Lisa Lambros, Nick Lambros, Jacqueline Miller, Jeff Miller, Anna Montes, Francis Podbielski M.D., Ron Ritzler, Tina Ritzler, Lou Schauer, Colleen Toriumi, Dean Toriumi, Dick Tryba, Mary Tryba, Andy Urbanski and Bozena Urbanski.