If you enjoy walking the paths of Central Park, you may notice that your experience is significantly more serene along the lower section of Ginger Creek. In September, the Oak Brook Park District completed a 2-year, $140,000 project to replace a failed gabion weir with a new rock Cross-Vane water control system.
The Ginger Creek gabion weir system was designed by Lindley and Sons, Inc. Civil Engineers in 1976. The project included three lagoons, a 2.75-acre reservoir and 3-acre reservoir that established channel boundaries and flood control that transformed the swampy portion of Ginger Creek to allow for more functional recreational opportunities and esthetically pleasing experience in Central Park. According to a 1976 Daily Herald article, the system was a “relatively obscure construction technique that dates to 19th century Italy” and was chosen for its erosion resistance and the speed and economy of installation.
Considered low-head dams, the weir structures were constructed of metal cages that resembled chicken wire filled with more than 160 tons of limestone. In 1987, just 10 years after the completion of the gabion weir project, Oak Brook experienced the worst flood in the history of Chicago, IL. According to the National Oceanic and Atmospheric Administration, a devastating series of thunderstorms dropped more than 9 inches of rain in just 8 hours, devastating Central Park. In its 1987 FEMA application, the park district reported a complete washout of the gabion weirs, path, and trees along Ginger Creek. In 1988, the weirs were completely replaced by the Milo-Gem Corporation.
By 2012, The negative ecological effects and danger of low-head dams had become well known and then Governor Pat Quinn announced an initiative to eliminate or modify 16 of them throughout the state. According to the IDNR’s website “the goal of the initiative was to improve water quality, aquatic habitat and recreational safety.”
Three short years later, in September of 2015 the eastern weir of Ginger Creek experienced a critical failure, causing a severe reduction of the water level in the center section of the creek.
According to Oak Brook Park District’s director of parks and planning, Bob Johnson, it was time to find another solution. “History has shown us that control systems like this reduce water quality, propagate shoreline erosion, create barriers to free upstream movement for aquatic life, and can create dangerous currents.”
After conducting extensive research, working with stakeholders and consulting with engineers, the park district determined that the best management approach with the most positive environmental impact was to eliminate the weir.
Knowing the park district was about to embark a larger improvement plan in Central Park, Johnson saw an opportunity to not only replace the failed weir, but implement further improvements to the watershed. His department implemented temporary erosion control measures along the creek, and Johnson began looking into funding options.
In March of 2018, the Oak Brook Park District was one of five agencies to receive a water quality grant from DuPage County. The grant awarded 18% of the funding for the native restoration of the Ginger Creek shoreline, green infrastructure, and the replacement of the east gabion weir.
In July, the park district began work on the lower section of Ginger Creek. The weir was removed, and extensive shoreline grading began to improve the severely eroded banks. “A wide bank with native plant species armors the shoreline against erosion,” says Johnson. When visiting the low section of Ginger Creek, instead of steep banks and exposed soil, you will see a gently sloping bank full of native grasses and flowers. The new native plantings will continue to develop over the next several years which will increase the natural beauty of the creek area, improve water quality, and provide healthy wildlife habitats as the plants become more established.
The weir itself was demolished and replaced with a step pool and rock vanes. The creek bed rock vanes were constructed exclusively using boulders that were excavated from the Central Park improvement project.
The vanes now allow water to pass through and over them, while maintaining the water level that was established after the gabion weir failed. This system not only allows for fish and wildlife to easily pass from one section of the creek to another, but also provides a natural way for the water to gently meet the shore. It also eliminates the severe churning of water from the low-head dam which caused a steady and eroding collision of water against the shoreline that continuously deposited sediment into the waterway.
Patrons have a unique opportunity to view the stark differences between the two water management systems, as there are no current plans to replace the weir in the upper section of the creek. The weir is divided in half by land lot boundaries and the Oak Brook Park District only owns one portion. The other section of the weir is the property of the McDonald’s Corporation.
About Ginger Creek
Ginger Creek is a tributary of the Lower Salt Creek Watershed, which flows through DuPage County. The Salt Creek Watershed is bounded by the Des Plaines River watershed on the east, and the DuPage River and Fox River watersheds on the west. Most of the creek’s watershed is urbanized and densely populated. According to the Salt Creek Watershed Network, improving the water quality of Ginger Creek and the Salt Creek “improves water quality all the way to the Gulf of Mexico.”
The Salt Creek Network: www.saltcreekwatershed.org
DuPage County: http://ec.dupageco.org/dec/saltcreek.htm
DuPage County Stormwater Management: https://www.dupageco.org/swm/
Daily Herald, November 11, 1976: https://www.newspapers.com/newspage/72132544/
Illinois Department of Natural Resources: https://www.dnr.illinois.gov/waterresources/pages/safetyatdams.aspx