This information describes the 2015-2020 project by The Morton Arboretum and the U.S. Army Corps of Engineeers to restore the East Branch of the DuPage River where it flows through the Arboretum.
Q: Why is the DuPage River restoration needed?
In the 1920s, the East Branch of the DuPage River was deepened and straightened so land along the riverbank could be used for agriculture, a common practice at the time. Since then, urbanization in the area around the river has increased the amount of paved and impervious surfaces—surfaces where water can’t be absorbed and runs off—leading to rapid increases in the flow of water following storms and highly fluctuating water levels. These changing conditions have eroded the riverbanks, threatening the trees, native plants, and wildlife that live there.
The DuPage River restoration will improve the river ecosystem to provide higher quality habitat for wildlife and native plants, and lead to lasting improvements for the enjoyment of visitors and the surrounding communities. The project also will safeguard the Arboretum’s important living tree collections by removing the threat of erosion. The project’s benefits will include improved water quality along the river and downstream; better habitat for fish, birds and other wildlife; greater plant diversity, including native grasses and wildflowers; removal of invasive trees and plants; and reduced erosion.
Q: What work is being done?
The project entails regrading the steep, eroded, clifflike river banks so the land slopes gently down to the river. This earth-moving work was done during 2016 on the stretch of river to the west of Illinois Route 53 and in 2017 to the east of Route 53. Once the regrading is complete in each area, the slopes and nearby floodplain are being planted with native plants, wildflowers, sedges, and grasses, as well as about 850 new native trees and shrubs. Within the river channel, boulders and other structures are being installed to vary the water flow, creating ripples and eddies and providing habitat for fish and other aquatic wildlife. As part of the project, 1,800 feet of drainage tile pipes within the floodplain have been disabled, allowing water to infiltrate the ground rather than quickly drain into the river. This will improve habitat for trees in our Eastern U.S. Wetlands Collection.
Q: How will the project affect Arboretum members, visitors, and neighbors?
The work will have minimal impact on neighbors of the Arboretum. Temporary road closures may be needed from time to time to keep people safe from construction equipment. Some trails will be either rerouted or temporarily closed when construction is underway.
Q: What is the relationship between the Arboretum and the U.S. Army Corps of Engineers?
The two organizations are partnering on the project. It has been a long-term goal of the Arboretum to improve the environmental health of the river for the well-being of trees, the quality of soil and water, and habitat areas for plants and wildlife along its route. As the nation's environmental engineer, the U.S. Army Corps of Engineers restores degraded waterways and related ecosystems. After a feasibility study determined the most beneficial and cost-effective way to restore the river, the Army Corps is executing the project and managing the work being performed on the Arboretum site.
Q: How long will the project take?
The most visible work, including tree removal, regrading, installing river features, and replanting, took place from 2015 through 2017. Regrading and replanting work was finished in 2016 on the Arboreum's West Side, along the stretch of river between Illinois Route 53 and Interstate Highway 88. In 2017, similar work was undertaken farther north, on a stretch of river that flows through the Arboretum along the east side of Route 53 south of the Hidden Lake Forest Preserve. It is expected to be finished by early 2018. Over the next few years, Arboretum staff and contractors will monitor the river and its floodplain as the plants grow and a greater diversity of plant and animal species develops.
Q: How much will the project cost?
The cost of the project is approximately $5 million, with the majority funded by the U.S. Army Corps of Engineers.