Wood River Drainage and Levee District lies in southwestern Illinois, on the left bank of the Mississippi River flood plain, within Madison County, Illinois, between river miles 195 and 203 above the Ohio River. The levee district is an urban design levee which lies across the Mississippi River from St. Louis and St. Charles Counties in Missouri. The Wood River levee system is part of a larger Metro East levee system that includes the Metro East Sewer District, Chain of Rocks, and Prairie du Pont and Fish Lake levee systems to the south.
The Wood River Flood Protection Project consists of three separate systems, Upper Wood River, Lower Wood River, and East & West Forks. This system includes approximately 21 miles of levee, 328 relief wells, 7 blanket drains, 2 cutoff walls, 26 closure structures, 41 gravity drains, 9 pump stations, and a low water dam. The study area lies in the Mississippi River flood plain of Madison County, Illinois, just upstream of the city of East St. Louis. There are approximately 12,700 acres of bottomland within the District and 4,700 acres of hill land tributary to the levee units.
The Wood River Flood Protection Project, constructed in the 1950’s, provided for raising and enlarging 20.8 miles of existing levee, construction of gravity drainage structures, closure structures at railroad and highway crossings, construction of new pump stations, surfacing of service roads on levee crowns, seepage control measures, and construction of a low-water dam at the mouth of Wood River Creek. The project, as intended, reduces the risk of flooding from an event up to a 52-foot Mississippi River stage on the St. Louis Gage, which has a current expected annual chance exceedance of less than .02%. The leveed area extends from the city of Alton, Illinois at the northwest end to the Cahokia Creek Diversion Channel at the southeast, protecting the industrial and urban areas of East Alton, Hartford, Roxana and Wood River. Additionally, the Wood River System provides upstream protection to the adjoining East St. Louis Levee System that extends from the Cahokia Diversion Canal to Dupo. In addition to reducing flood risks to the leveed area, the levee structure is a part of the containment features for the Melvin Price Locks and Dam Project.
Replacement of Lock and Dam 26, which resulted in construction of the Mel Price Locks and Dam from 1979 to 1994, raised the height of the navigation pool on an approximate 2 mile stretch of the existing levee, increasing seepage in this levee stretch and necessitating the construction of a new pump station at East Alton. The Mel Price pool is maintained during low water, however it is much lower than the design flood and does not impact the water surface profile used for design of relief wells at the authorized level because it would be operated under open river during a high water event.
Construction was completed in 2008 for the Grassy Lake pump station, located on the south flank of the district, which addresses interior water impounded by the existing levee. A contract and task order was awarded in November 2008 for relief well construction recommended by the General Reevaluation Report (GRR). A subsequent task order was awarded in September 2009 for additional relief well construction.
The Water Resources Development Act of 2007 authorized the reconstruction work recommended by the GRR. The initial reconstruction contract for gravity drain repair was awarded in September 2009. Subsequent contract awards were made in November 2009 (Phase 1 Gravity Drain Repairs), May 2010 (Phase 2 Gravity Drain Repairs), June 2010 (Pump Station Reconstruction), August 2010 (Closure Structure Reconstruction), September 2011 (Grassy Lake Gravity Drain Repair), September 2013 (Wood River Relief Wells at East Alton No. 1 Pump Station), and September 2014 (Miscellaneous Repairs).
In July 2009, the Southwestern Illinois Flood Prevention District Council (FPD Council) was formed in direct response to the Department of Homeland Security’s Federal Emergency Managements Agency (FEMA) 2007 announcement of its intention to de-accredit the 65-miles of levee systems protecting the St. Louis Metro East region, including the Wood River Flood Protection Project. The FPD Council designed and constructed several levee system improvements over the next several years to maintain the region’s accreditation in accordance with the National Flood Insurance Program (NFIP) requirements as described in 44 CFR Section 65.10. Construction projects completed by the FPD Council in the Wood River Flood Protection Project area include:
- Bid Package 2B – Levee Pump Stations (Completed March 2018)
- Bid Package 03 – Underseepage Control Improvements (Completed October 2017)
- Bid Package 7A – Upper Cutoff Wall (Completed July 2015)
- Bid Package 7B – Lower Cutoff Wall (Completed October 2017)
In March 2021, the Wood River Drainage and Levee District received letters of continued accreditation for all three levee segments from the U.S. Department of Homeland Security’s Federal Emergency Management Agency (FEMA). This means that the Upper Wood River Levee System, Lower Wood River Levee System, and the East and West Fork Levee System are each certified to provide protection against a flood event with a 1% annual chance of occurrence, commonly known as the 100-year flood.
Beginning in fall 2021, the U.S. Army Corps of Engineers (USACE), in cooperation with the FPD council and the Wood River Drainage and Levee District, will be constructing additional improvements that will provide protection against a flood event with a 0.2% chance of occurrence, commonly known as the 500-year flood.