US Army Corps of Engineers
Chicago District

DuPage River Feasibility Study

FAQ & SUMMARY OF INITIAL PUBLIC REVIEW:

A summary of the public comments received and responses to frequently asked questions can be found here: Summary of Public Comments

CURRENT STATUS -- SECONDARY PUBLIC REVIEW: On May 2, 2019, the U.S. Army Corps of Engineers, Chicago District released for public review the DuPage River, Illinois Feasibility Report and Integrated Environmental Assessment. The report is available for review here – links to the documents are on the right side of this page.

The Army Corps of Engineers is accepting comments on the report for 15 days from May 2, 2019, through May 17, 2019. Comments may be submitted by e-mail to dupageriver@usace.army.mil or mailed to: U.S. Army Corps of Engineers, Chicago District, 231 S. LaSalle Street, Ste. 1500, Chicago, IL 60604, ATTN: DuPage River. Mailed comments must be postmarked by May 17, 2019.

This is a secondary public comment period of the report with an updated recommended plan. An initial review of the Tentatively Selected Plan (TSP) was conducted from August 1, 2018 through September 22, 2018. At that time, the TSP consisted of the Lisle Levee and nonstructural measures across the watershed.  Following public, state and agency, and USACE and independent review of the TSP, more detailed engineering and economic analysis was completed to refine the recommendations for this study. Based on completion of this more detailed analysis, the refined results indicated that the Lacey Creek Restriction was economically justified and supportable and therefore it was determined that the Lacey Creek Restriction could be included in the Recommended Plan. Due to the addition of this feature in the recommendation, USACE determined that conducting a second review period was warranted.

AUTHORITY:  This effort is authorized by Section 206 of the 1958 Flood Control Act (PL-85-500), which includes the Chicago – South End of Lake Michigan (C-SELM) Urban Water Damage Study Authority. This Authority directs studies for flood control and allied purposes within the watershed of the Illinois River in the vicinity of Chicago Illinois, which includes the DuPage River Watershed.

DESCRIPTION:  This study was completed to investigate overbank and backwater flooding along the DuPage River and its major tributaries, which are tributary to the Illinois River, prioritizing high-risk areas and developing a range of possible structural and nonstructural alternatives to address flood risks. The study area has experienced rapid development over the past several decades and currently includes 40 communities and over 1 million residents.

As part of this study, an assessment of existing and projected future without project conditions over a 50-year period of analysis was completed.  The analysis, which included hydrologic, hydraulic, and economic modeling, determined that a significant risk of overbank flooding exists in a number of locations across the watershed. Expected annualized flood damages are estimated at $5,317,000 for this study.

STUDY AREA:  The DuPage River and tributaries drain approximately 353 square miles in suburban Cook, DuPage and Will counties in Illinois. The study area has experienced rapid development over the past two decades, and currently includes 40 communities and approximately 900,000 residents. Major storm events resulting in overbank flooding in the basin occurred in 1996, 2008, 2009, and most recently in April 2013. The April 2013 flood impacted at least 20 communities and caused significant damage to residential and non-residential structures, critical infrastructure and the closure of two major interstate highways (I-80 and I-55) for several days.

Communities within DuPage County where flooding will be evaluated include, but are not limited to: Bartlett, Carol Stream, Glen Ellyn, Hanover Park, Lisle, Lombard, Naperville, Roselle, Warrenville, West Chicago, Westmont, Winfield and Woodridge. Communities within Will County include, but are not limited to: Bolingbrook, Joliet, Romeoville, Crest Hill, Plainfield, Minooka, Channahon, Plainfield Township, and Wheatland Township. 

RECOMMENDED PLAN

The Recommended Plan includes structural and nonstructural measures

The two structural components included in the plan would provide flood risk reduction on the East Branch primarily within the Village of Lisle. The Lisle Levee project would be improved and elevated to approximately the 1% ACE flood profile elevation. The Lacey Creek restriction would act to reduce peak flows on the East Branch downstream of the Lacey Creek Confluence with the East Branch, particularly in the Lisle Area.

Lisle Levee Elevation: The existing Lisle Levee was originally constructed in 1961, with the levee crest elevation at the approximate level of the 2% annual chance exceedance (ACE), also referred to as the 50-year flood event. Deterioration of the levee has occurred over time, lowering the crest elevation in some areas and eroding the side slopes and levee toe. Based on the current condition and height of the Lisle Levee, it has been identified as at risk of overtopping or failure. This study recommends repair of the several segments of the existing structure to USACE levee standards by removal of large woody debris, re-grading of side slopes, repair of eroded areas, and riverside toe armoring. The project would also elevate the levee to approximately the currently identified 1% ACE (100-year) flood elevation to provide additional risk reduction. To complete the line or protection, an additional tie-back along the east bank of the East Branch just South of Ogden Avenue as well as a closure structure on Illinois Route-53, which will be operated during high water conditions, will be required. The project would provide flood risk reduction to approximately 175 structures located behind the existing levee.

Lacey Creek Restriction: The Lacey Creek Restriction is proposed to limit outflow from the Lacey Creek Tributary to reduce the peak flow entering the East Branch from that tributary.  The project will store approximately 283 acre-feet of floodwater and slowly release it to the East Branch, lagging behind the larger East Branch flood pulse, which will reduce peak flows and stages on the East Branch downstream of the Lacey Creek. Project features include an earthen berm with a primary, restrictive outflow culvert in addition to an operable gate which could facilitate more rapid drawdown of the storage area after floodwaters have receded to reduce impacts to habitat upstream.  Impacts to aquatic habitat will be mitigated as part of the project construction. 

The nonstructural components of the plan provide flood risk reduction through acquisition, elevation, or floodproofing structures. Nonstructural features are included within the communities of Shorewood, Plainfield, Bolingbrook, Lisle, and Glen Ellyn . The nonstructural plans include modifications of 38 structures including likely acquisition of 6 structures, elevation of 9 structures, and floodproofing of 23 structures.

HISTORY: On July 14, 2015, the U.S. Army Corps of Engineers, Chicago District, signed a Feasibility Cost Share Agreement (FCSA) with the DuPage County Stormwater Management Planning Committee and Will County Executive Office, which initiated the study.

During the initial phase of the study, the partners collected available data and developed preliminary alternatives to address the flood risks. This initial phase included public scoping as required by the National Environmental Policy Act (NEPA) and coordination with Federal, state, and local resource agencies. Once the scoping phase was completed, the Corps and the non-Federal sponsors began the process of developing computer models to simulate flooding and flood impacts in the watershed. The computer models use rainfall estimates, river capacity, and inventories of structures and infrastructure at risk to estimate potential impacts. These models allowed the study team to estimate the likely extent of flood risks and evaluate how effective proposed projects would be for managing those risks.

The study team also identified possible solutions to flood problems. The potential projects included levees, floodwalls, storage reservoirs, changes to bridges that obstruct the river, changes to the channel to increase its capacity, diversions to redirect floodwater around areas at risk of flooding, and non-structural measures such as buyouts and floodproofing. All of the information developed for the study has been coordinated with representatives of the communities at risk of flooding.

PRESENTATIONS FROM PUBLIC MEETINGS - NOVEMBER 2015:

Public meetings were held to present the “Tentatively Selected Plan” on Wednesday, Aug. 15, 2018, in Wheaton, Illinois and Thursday, Aug 15, 2018 in Plainfield, Illinois.

Copies of the presentations from those meetings: Public Meeting DuPage River

Public meetings were held Monday, Nov. 16, 2015, in Bolingbrook, Illinois, and Tuesday, Nov. 17, 2015, in Wheaton, Illinois, and Wednesday, Nov. 18, 2015, in Shorewood, Illinois.

Copies of the presentations from those meetings: Public Meeting DuPage River 15AUG2018

U.S. Army Corps of Engineers presentation about the DuPage River study

Presentation from DuPage County Stormwater Management

Presentation from Will County

NONFEDERAL SPONSORS:  DuPage County and Will County

UPCOMING PUBLIC MEETINGS